## Solar System (9)

### The water D/H ratio in a TOO long-period comet

Proposal ID: OT2_dbockele_2

Principal Investigator: Dominique Bockelee-Morvan

Time: 7.7 hours priority 1

Category: Comets

Summary:

Having retained and preserved pristine material from the Solar Nebula at the moment of their accretion, comets contain unique clues to the history and evolution of the Solar System. Important diagnostics of how and where cometary materials formed are contained in isotopic ratios, since isotopic fractionation is very sensitive to chemical and physical conditions. Following the discovery of an Ocean-like D/H ratio in the water of the Jupiter-family comet 103P/Hartley 2 using HIFI (Hartogh et al. 2011, Nature, in press), we propose to obtain a high-accuracy D/H measurement in a long-period comet from the Oort cloud. Since measurements in Jupiter-family comets have only been acquired with Herschel, it is important to get a set of measurements for Oort cloud comets with the same instrumentation. Confirming the observed dichotomy in D/H ratio for long-period versus Jupiter-family comet would be the first clear compositional difference between these two dynamical classes of comets. The values and statistics of distribution of the D/H ratio in the two classes will improve our understanding of their origin in the Solar System, with implications for the dynamical evolution of the early Solar System and for the delivery of water and other volatiles to the Earth.

### Galactic Background Calibrations for OT1_ddan01_1 Detecting the Largest Rings in the Solar System--Dust Rings from the Irregular Satellites

Proposal ID: OT2_ddan01_2

Principal Investigator: Daniel Tamayo

Time: 4.3 hours priority 2

Category: Solar System Other

Summary:

This is a follow-up proposal to our ongoing OT1 proposal "Detecting the Largest Rings in the Solar System--Dust Rings from the Irregular Satellites" (OT1_ddan01_1). We seek to re-image each field visited by our OT1 observations once the planet and its rings have moved out of the scan. This will allow us to accurately subtract the galactic background that currently obscures our data. The cirrus emission represents the last barrier to accurate photometry at uninvestigated wavelengths of the newly discovered Phoebe ring at Saturn(Verbiscer et al. 2009), as well as the possible discovery of analogous rings around Uranus and Neptune. The total time required (including overheads) is 11.8 hours as estimated by HSpot.

### Pluto's seasonal evolution and surface thermal properties

Proposal ID: OT2_elellouc_2

Principal Investigator: Emmanuel Lellouch

Time: 10.2 hours priority 1

Category: Kuiper Belt bodies

Summary:

In 2015, Pluto and its system of satellites will be explored by the New Horizons space mission. Pluto is the most prominent representative of large Kuiper-belt objects with volatile ices (N2, CH4, CO) on their surfaces. Due to its elliptic orbit and strong polar inclination, the large seasonal and spatial variability of the insolation is expected to drive global scale transport of the volatile ices, whose thermal balance determines the atmospheric state. Recent observations of Pluto of various kinds have revealed that it is undergoing seasonal evolution, with changes in its atmosphere, surface spectrum, and thermal emission. In particular, Spitzer observations over 2004-2007 indicated a surprising dimming of the dwarf planet at thermal wavelengths, most probably associated with extension of the coldest, N2-ice dominated, regions. We propose to measure the thermal lightcurve of the Pluto/Charon system (i.e. the rotational variation of its thermal emission) with PACS and SPIRE in order to (i) assess the changes in the ice distribution (ii) determine the emissivities (spectral and bolometric) of Pluto's different terrains (iii) determine their thermal inertia on seasonal timescales. These parameters are needed to constrain volatile transport and general circulation models, and to put the upcoming New Horizons measurements in a broader, time-evolving, perspective.

### Probing the Enceladus torus with Herschel

Proposal ID: OT2_elellouc_3

Principal Investigator: Emmanuel Lellouch

Time: 11.7 hours priority 1

Category: Planets

Summary:

### Herschel Space Observatory observations of outburst and split comets

Proposal ID: OT2_itoth_2

Principal Investigator: Imre Toth

Time: 13.9 hours priority 2

Category: Comets

Summary:

Our primary goal is to increase our knowledge about the outburst and split comets using the both the Herschel Space Observatory and ground-based telescopes in order to combine the thermal infrared and visible domain data. Our comet targets are selected from different orbit classes as like Ecliptic Comets (ECs), Nearly-isotropic Comets (NICs), and Main Belt Comets (MBCs). These are 17/PHolmes (EC), the most puzzling comet underwent already two superoutbursts, 133P/Elst-Pizarro (MBC) which shows recurrent cometary activity, 213P/Van Ness (EC) is a split comet with two components, and C/2010 X1 (Elenin) is a split and outburst comet. Comparison of the thermal infrared and visible range observations allows to investigate the shape and possible surface inhomogenities using infrared flux curves and light curves in the visible. We will use the unique capability of the PACS instrument of the Herschel Space Observatory. The measurements for all targets are performed in scan map mode, observations are done priimarilz in the PACS blue (70 micron) band. By means of this observational technique we will reach 1/1.5 mJz in the 70 micron band. The proposal will cover total observing time schedule of 13.9 h.

### A Search for Gaseous H2O in Asteroids (24) Themis & (65) Cybele

Proposal ID: OT2_lorourke_17

Principal Investigator: Laurence O'Rourke

Time: 2 hours priority 1

Category: Asteroids

Summary:

The detection of water ice on Asteroids (24) Themis and (65) Cybele and comet-like activity on some asteroids (so-called main belt comets) have recently provided evidence for water ice in the outer asteroid belt. This supports the suggestion that water in the Earths oceans may have been delivered from the outer asteroid belt.

In 2010, for both (24) Themis and (65) Cybele, results were published from rotationally resolved near-IR spectra that indicated the presence of widespread ice on their surfaces, a detection which served to imply a wider prevalence of water among minor Solar System bodies. However, this detection has since been challenged in 2011 with an alternative interpretation of the absorption at 3.1 microns being suggested.

This proposal requests 2 hours of the Herschel Space Observatory’s HIFI instrument scheduling time, 1 hour observation per asteroid, to provide conclusive evidence of the presence of water ice on these asteroids through the detection of outgassing via sublimation of this water; a result which has profound implications on the understanding of the origin of water on our planet.

### Titan's Ammonia Cycle

Proposal ID: OT2_nteanby_4

Principal Investigator: Nicholas Teanby

Time: 8.1 hours priority 2

Category: Satellites

Summary:

Titan's atmosphere has one of the most complex photochemical cycles in the solar system and results in a vast array of organic compounds containing H, C, N, and O. Understanding Titan's atmosphere has been a major scientific goal since the Voyager era and was one of the main drivers for the Cassini mission. When Cassini first flew through Titan's upper-most atmosphere its mass spectrometer discovered unprecedented levels of ammonia (NH3), which were orders of magnitude greater than those predicted by the most up-to-date photochemical models. This discovery suggests serious deficiencies in our present understanding Titan's photochemical cycle.

Based on the Cassini upper atmosphere measurements, it is now suspected that NH3 is present throughout Titan's bulk atmosphere in much greater quantities than previously expected. This has recently lead to an additional NH3 production pathway being hypothesised - which we aim to test in this proposal. By observing NH3 spectral emission lines around 1764 GHz with Herschel's HIFI instrument it will be possible to determine the bulk atmosphere NH3 abundance for the first time. This will allow us to probe missing links in Titan's ammonia and nitrogen cycles and dramatically increase our understanding of Titan's atmosphere and photochemical processes in general.

### The origin of CO in Uranus

Proposal ID: OT2_tcavalie_6

Principal Investigator: Thibault Cavalie

Time: 8 hours priority 1

Category: Planets

Summary:

One of the Infrared Space Observatory's most important results is the detection of H2O and CO2 in the giant planet stratospheres. The presence of a condensible species (H2O) above the tropospheric cold trap implies an external origin of H2O. This oxygen supply, which manifests itself also through the presence of CO2 and CO in these atmospheres, may have several sources: a permanent flux from interplanetary dust particles, local sources (rings, satellites), or large comet impacts. However, observing CO in the stratospheres of the giant planets does not automatically imply only an external origin of this species because there is no condensation sink at the tropopause for CO. Thus, it can be transported from the deep hot interior of the planet to the stratosphere. CO can have either an internal origin, an external origin or a combination of both. Spectrally-resolved, high signal-to-noise ratio and spatially-resolved (when possible) observations are needed to disentangle the various sources. While Jupiter, Saturn and Neptune have all an external source of CO, probably of cometary origin, and an internal source (not yet demonstrated but likely in Saturn), the situation remains unclear at Uranus despite the detection of CO from its 5 micron fluorescence. So far, we have not detected CO from the ground in the (sub)millimeter range but we obtained a tentative detection of the CO(8-7) line with HIFI in July 2011 in the framework of the HssO Key Programme. Because external sources of CO seem to be active for all the other giant planets, we propose to observe Uranus at the frequency of the CO(8-7) line with HIFI in order to confirm our tentative detection in the submillimeter range. We will obtain a spectrally-resolved and high signal-to-noise ratio observation of the lineshape that will enable us to retrieve information on its vertical distribution. Thus, we will be able to discuss the origin of CO in Uranus from this observation.

### Probing the temperature and chemistry of Saturn's storm with Herschel

Proposal ID: OT2_tcavalie_7

Principal Investigator: Thibault Cavalie

Time: 11.7 hours priority 1

Category: Planets

Summary:

Saturn's usually slowly evolutive seasonal cycle has been disrupted in December 2010 between 20°N and 50°N by the outbreak of an unexpected huge storm system. First Cassini/CIRS and ground-based observations have shown that temperatures, winds and chemistry have been rapidly affected by the storm in the stratosphere. For instance, a temperature increase of 50K over 60° in longitude has been measured by Cassini/CIRS in May 2011. We propose to take advantage of this rare opportunity to use Herschel’s mapping capability with HIFI and PACS to probe the vertical structure of this unique storm and derive constraints on its formation processes. We will map the emission of H2O at 66 and 67 microns and CH4 at 120 microns and 1882 GHz to measure the temperature between 0.1 and 100 mbar in the stratosphere and to check for any disturbance in the H2O vertical profile. Such disturbance would be due to the injection of massive amounts of tropospheric H2O into the stratosphere by the storm. Because this storm seem to undergo a slow evolution, we propose to monitor its temporal evolution by observing the proposed set of maps once in each of the three remaining observability windows of Saturn.

## ISM/Star formation (158)

### Herschel Spectroscopy of Spitzer's Extended Green Objects: Tracing the Earliest Stages of Massive Star Formation

Proposal ID: OT2_aboogert_2

Time: 13.5 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Massive star formation remains a poorly understood phenomenon, largely due to the difficulty of identifying and studying massive young stellar objects (MYSOs) in the crucial early active accretion and outflow phase. Large-scale Spitzer surveys of the Galactic Plane have yielded a promising new sample of young MYSOs with outflows, which are likely actively accreting: based on their extended 4.5 um emission in Spitzer images, these sources are known as "Extended Green Objects (EGOs)" from the common coding of three-color IRAC images. Extensive ground-based follow up observations revealed that the EGOs are indeed related to massive outflows from young systems with very high accretion rates (10^-3 Msun/year). They also revealed a wide variety of properties: some MYSOs appear in clusters, others are isolated, some are molecular line rich, others not. To test the hypothesis that these differences reflect evolutionary effects, we propose SPIRE/FTS and HIFI observations of 4 EGOs. SPIRE/FTS spectra of the 12CO and 13CO rotational ladders and HIFI spectra of selected CO line profiles would yield shock-excited gas temperatures and masses, constraining the current outflow (and thus accretion) activity in a more direct way than is possible in low excitation tracers with ground-based telescopes. HIFI observations of H2O and NH3 line profiles and abundances would provide independent present day outflow activity indicators and records of the shock history, as these species are formed above temperatures of 230 and 4000 K, respectively, and preserved in the post-shock gas. This unique Herschel data set would also address outstanding questions about the disputed origin of the Spitzer "green" emission, interstellar H2O/NH3 abundance ratios, and the role of outflow feedback in models of cluster formation.

### High Velocity Cloud Properties and Origins Traced by CII Emission

Proposal ID: OT2_aford_1

Principal Investigator: Alyson Ford

Time: 9.4 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

The Galactic high velocity clouds are typically 10 kpc from the Sun, with many moving at high speeds through the hot (million Kelvin) gaseous halo. In addition to photoelectric heating, ram pressure can thus also heat the clouds. These heat sources are balanced by the infrared forbidden line emission of C II and O I, providing a direct window to the relevant heating processes. One particular anti-center HVC is a likely CII 158 um source, based on our study of the COBE FIRAS 158 um map and all-sky HI data. Unfortunately, the FIRAS resolution (7 degrees) is too poor to determine the location relative to the cloud and contains no useful velocity information. With the proposed Herschel PACS spectral study, we will determine whether the CII enhancement occurs at the leading side of the cloud as it falls onto the Galaxy, and the degree of ram pressure heating compared to photon heating; the C II velocities also provide crucial information. In addition, we will determine the temperature and abundance of carbon and oxygen, which will indicate if the HVC is Galactic (solar metallicity) or low-metallicity accreting material.

### Observing Young Debris Disks with SPIRE

Proposal ID: OT2_agaspar_1

Principal Investigator: Andras Gaspar

Time: 2.2 hours priority 2

Category: Circumstellar/Debris disks

Summary:

The process by which planets accrete and grow are not fully understood. A unique insight could be provided by measuring the size distribution of the collision products in young systems, as it would constrain their dynamical state and the composition of their planetesimal bodies. We propose to observe twelve systems with SPIRE, determining the particle size distribution slope from their long wavelength photometry, breaking the size distribution/distance degeneracy in their SED models by combining our new data with existing Spitzer and IRAS photometry and determining the geometry of the systems.

The thermal signature of planetary debris disks typically originates from particles up to a thousand microns in size and it typically takes on the order of twenty to thirty million years for particles of that size to reach collisional equilibrium in warm disks and 100 to 200 Myr in cold disks. The distribution of dust in the earliest stages of evolution should be more reflective of the collisional fragmentation function and the effects of aggregation between the smallest particles than the collisional cascade equilibrium distribution function, which is reached at a later stage. The slope of the SED in the Rayleigh-Jean regime is in direct relation to the slope of the particle size distribution. While the particle size distribution in older disks can be approximated via models, it is completely unknown for young systems. With SPIRE we will be able to directly observe the particle size distribution in the earliest stages of debris disk formation, which will then shed light on the nature of planetesimal bodies and their formation!

### Mapping Water and related Hydrides in Massive Protostellar outflows with HIFI

Proposal ID: OT2_agomezru_2

Principal Investigator: Arturo Gomez-Ruiz

Time: 7.5 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

Massive outflows are known to drive a special chemical complexity due to the strong shocks they produce in the surrounding molecular material. Hydrides are key ingredients of interstellar chemistry since they are the initial products of chemical networks that lead to the formation of more complex molecules. Given their small reduced masses, their rotational lines lie at short sub-mm wavelengths, which are almost unobservable from the ground. With the HIFI instrument on board of the Herschel satellite it is now possible to observe the strongest transitions of light hydrides, in particular H2O but also the reactive ions OH+ and H2O+, which are thought to play a crucial role in the formation of OH and H2O. HIFI early results revealed that indeed water and its cation H2O+ are abundant components of the interstellar medium. The additional HIFI detection of OH+ is an important confirmation of the gas-phase route of water. Although key programs have targeted few massive sources to map the water distribution, a comprehensive study including other important hydrides such as OH+ and H2O+, and covering sources in different evolutionary phases, has not been provided yet. This project proposes a dedicated study of water and related hydrides (H2O+ and OH+) in massive protostellar outflows in order to: a) trace the water distribution throughout the different evolutionary phases of massive star formation, b) determine the contribution of water emission in the energy lost by shocks, and c) unveil the role of ions such as OH+ and H2O+ in the production of water.

### Outflow evolution in high-mass star formation

Proposal ID: OT2_alopezse_2

Principal Investigator: Ana Lopez-Sepulcre

Time: 19 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

The formation mechanism of high-mass stars and the different evolutionary phases involved in the process, still remain unclear. We recently performed single-dish HCO+ and SiO observations at millimetre wavelengths of a sample of high-mass star forming regions in search of molecular outflows. Our results indicate a decrease in the jet/outflow activity with the luminosity to mass ratio, L/M, a distance-independent parameter considered to be an estimate of time or evolutionary state. These findings are analogous to what is found in the low-mass case, which suggests that high-mass stars may form in a similar way to low-mass stars. However, uncertainties such as the unknown inclination of the outflow axes and the poor knowledge of HCO+ and SiO abundances call for more precise measurements of the outflow mass loss rates to assess the variation of this quantity with time and also associate them with the accretion rate, a crucial parameter to understand high-mass star formation.

We therefore propose to image a suitably selected sub-sample of the regions with outflows with PACS in the OI 63 micron line. According to theory, this line can be related to the outflow mass loss rate, which can thus be easily obtained. Combined with our single-dish outflow maps, and with data from the Hi-GAL survey for a better estimate of the luminosities and masses, we will calculate all the relevant parameters to assess the dependence of outflow rate on time for high-mass stars. We will also observe the OI 145 micron line to check for possible opacity effects, the CII 157 micron line to verify the presence of photo-dissociation regions which could affect the OI emission, and a number of CO transitions with both PACS and SPIRE to analyse the excitation conditions of the outflows.

### Mapping the cosmic ray ionisation rate across the Northern end of the Orion A iant molecular cloud

Proposal ID: OT2_alopezse_3

Principal Investigator: Ana Lopez-Sepulcre

Time: 5.2 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

Cosmic rays (CR) are ubiquitous in the Galaxy and have the important role of ionizing the dens gas of the ISM. New Herschel observations have shown the huge diagnostic power of the OH+ fundamental transition to measure the CR ionization rate in diffuse clouds. Based on previous "serendipity" observations toward OMC2-FIR4 within the KP CHESS, we discovered a tenuous foreground cloud absorbing the fundamental OH+ line. Similarly, Gupta et al. (2010) found an OH+ absorption component at a similar velocity towards Orion KL and estimated a large CR ionization rate more than 10 times larger than the average value observed in diffuse clouds . We propose here to roughly map the CR ionization rate in the direction of the OMC2 and OMC3 complex to understand its extent, nature, and, finally, the source of ionization.

### The origin of gas in the two oldest newly discovered gaseous debris disks.

Proposal ID: OT2_amoor_3

Principal Investigator: Attila Moor

Time: 9.2 hours priority 1

Category: Circumstellar/Debris disks

Summary:

Many young main-sequence stars are surrounded by dusty debris disks, but only very few of them have a detectable gas component. In our APEX survey we discovered two new debris disks containing a substantial amount of molecular CO gas. One of them, the 30 million-year-old HD 21997, is the oldest known gaseous debris disk, making it the best candidate for containing CO gas of secondary origin, produced by sublimation of planetesimals, photodesorption from dust grains, or vaporization of colliding dust particles. We suggest that our discoveries together with the already known objects beta Pic and 49 Ceti form a distinguished group of debris systems that may represent the first stage of gas evolution after the primordial phase. Here we propose new Herschel observations to deduce the physical properties and the origin of gas in our targets, and study the possible physical processes of gas production in the secondary origin scenario. Our immediate objectives are the following: 1) Detection of [O I] 63um and [C II] 158um lines in our targets; 2) physical characterization of the gas/dust disk components; 3) establish the origin of gas and 4) comparison with beta Pic and 49 Ceti, and studying evolutionary aspects. The observation of atomic emission lines in such disks will provide a valuable information on the composition of the released gas and thus on similarity of the volatile composition of Solar System comets to exosolar planetesimals, potentially playing key role in the delivery of volatiles to exoplanets. The study request 9.2h observing time.

### A census of debris disks in nearby young moving groups with Herschel.

Proposal ID: OT2_amoor_4

Principal Investigator: Attila Moor

Time: 28.7 hours priority 2

Category: Circumstellar/Debris disks

Summary:

Nearly all young stars harbour circumstellar disks, that serve as the reservoir for mass accretion onto the star, and later become the birthplace of planetary systems. After the disappearance of the gas component from the disk a dusty debris disk is formed that is believed to mark the location of the planetesimal belt as well. For outlining the evolution of such debris disks traditionally open clusters and field stars were studied, however we argue that the recently discovered young moving groups are more suitable objects for such analyses, due to their proximity and good coverage of the first 50 Myr period of the planetary system evolution. In this proposal we request 70/160 um Herschel/PACS photometric observations for so-far unobserved moving group members. These observations will provide a complete coverage of all known members within 80 pc of five nearby young moving groups (beta Pic Moving Group, Tucana-Horologium, Carina, Columba, and Argus), in the A to K spectral range. Based on the new observations we will identify new debris disks, characterize the disk population within individual moving groups, and study disk evolution by comparing the groups of different ages. The results will be used to verify predictions of the self-stirring model of the evolution of planetesimal disks. We will also compare the properties of debris disks in groups of the same age, looking for additional 'environmental' parameters that affect disk structure over a whole moving group. Our study will be a significant contribution to the census of debris disks in young moving groups, increasing the number of observed sources by a factor of 1.5. Since Spitzer could perform only a limited census and the so-far approved Herschel programs added very few additional moving group obervations, our programme is expected to have a high legacy value.

### SABER: Spectral Analysis of the Bowshock Emission in a Runaway

Proposal ID: OT2_anoriega_2

Principal Investigator: Alberto Noriega-Crespo

Time: 6.2 hours priority 1

Category: Galactic Other

Summary:

Bowshocks around runaway OB stars are some of the most spectacular objects in the mid/far infrared, covering in some cases as much as half a degree across the sky. The bowshocks are essentially enormous gas shells contained by ram pressure where the dust trapped in their interiors reprocesses the UV flux from the parent OB stars and re-radiates it in the infrared. The pressure balance between the stellar wind and the ISM, also implies a tight relationship between their physical properties, and therefore, bowshocks from runaway stars provide a powerful tool to probe the interstellar medium and/or the properties of the OB stellar wind. The formation of these shells requires very efficient cooling that is expected to take place through the emission of a wealth of atomic fine structure lines, like [OI] 63.2 or [NII] 205.2 micron. Because the diffuse nature of these shells it has been very difficult to confirm this expectation using spectroscopic observations. In this project we propose to use the PACS spectrometer to observe the zeta Oph bowshock in order to better understand and constrain the physical conditions of its gas shell, its dust properties, its turbulence, and in such a way that will allow to use zeta Oph as a template to make sense of the physical properties of the many more runaway bowshocks are continuously being discovered.

### Ultra-Cold Material in Young Debris Disks

Proposal ID: OT2_aroberge_3

Principal Investigator: Aki Roberge

Time: 3.2 hours priority 1

Category: Circumstellar/Debris disks

Summary:

Disks of gas and dust around young stars evolve from massive, gas-rich protoplanetary disks to tenuous disks mainly of dust. These dusty disks, now called debris disks, are produced by colliding and evaporating planetesimals, young analogs of Solar System asteroids and comets. They are intermediate between dense protoplanetary disks and mature extrasolar planetary systems.

Herschel disk surveys have found a number of systems with exceptionally cold debris dust, which is likely a sign of planetesimal belts at surprisingly large distances from the central stars (> 50 AU for a solar-type star) and/or peculiar dust properties. These systems will provide key tests of theories for debris disk evolution and planet formation. However, observations at longer wavelengths are urgently needed to 1) truly measure the dust abundances and temperatures, 2) find any dust components at even colder temperatures, and 3) permit accurate modeling of the dust properties and spatial distributions.

Therefore, we propose confusion-limited SPIRE photometry at 250, 350, and 500 microns for 24 debris disks in nearby young associations, to populate an important region of their spectral energy distributions. The targets are located in the TW Hydra Association, the Upper Scorpius Association, the Beta Pictoris Moving Group, and the Tucana-Horologium Association, spanning a crucial age range for debris disk evolution (10 to 30 Myr). The proposed observations, which are uniquely sensitive to ultra-cold dust, require a total of 3.2 hours. Our targets have all been observed with PACS but not with SPIRE. This proposal is independent (stand-alone) in its goals and execution: in short, we are looking for ultra-cold dust in a sample of young debris disks. However, the final dataset will also increase the legacy value of several other Key Programme datasets.

### A Study of Cold Disks around M dwarfs and the Formation of Extrasolar Planets

Proposal ID: OT2_atanner_1

Principal Investigator: Angelle Tanner

Time: 27.1 hours priority 2

Category: Brown Dwarfs/Very Low-Mass Stars

Summary:

M dwarfs are the most populous stars in our local universe, and yet we know little about how they form and how often they form planetary systems. Due to smaller stellar radii, larger gravitational reflex motions, and closer habitable zones, M dwarfs are ideal targets for detecting the first terrestrial mass planets in the habitable zone and will be high priority targets for years to come. Therefore, studying the population and physical characteristics of circumstellar disks around M dwarfs will provide insights into this unique environment in which we hope to find habitable planets. Here, we propose to use the Herschel telescope to collect far-infrared (100 & 160 micron) photometry of a sample of 32 M dwarfs. Our sample represents the best candidates to contain detectable debris disks based on youth and proximity to Earth. Our science goals will be to characterize the physical properties of these disks such as temperature, extent and composition thereby gaining a deeper understanding of the formation and evolution of the planetary systems around low-mass stars. This will also identify the best targets for terrestrial planet search programs based on recent Kepler findings.

### Studying the collisional processes in the debris disk of Beta Pictoris

Proposal ID: OT2_bdevries_5

Principal Investigator: Ben de Vries

Time: 16.4 hours priority 2

Category: Circumstellar/Debris disks

Summary:

Beta Pictoris is a young (12 Myr) main-sequence star surrounded by at least one planet at a distance of ~10 AU, and a dusty debris disk created by catastrophic collisions of planetesimals. We propose to make a deep observation of the 69 micron band of crystalline olivine in the debris disk of Beta Pictoris. The debris disk is resolved with HERSCHEL-PACS. This will enable us to study the collisional processes within the debris disk. The discovery of more than 600 exo-planets in the past two decades has shown an amazing diversity in the properties of planetary systems. The origin of this diversity and the way the solar system fits in must be understood by studying young systems in which planet formation is ongoing, and by comparing the properties of these young systems with the historic records of the formation of the solar system as recorded in e.g. asteroids and comets. Beta Pictoris is a unique object for this, since it is bright and it still shows spectral features since it is young enough to still have small grains. Previous studies have already shown that the crystalline olivine material in Beta Pictoris is very similar to that in our own Solar System. Using the integral-field-spectrometer PACS we will be able to look at the 69 micron band of crystalline olivine at the position where the material is created and further out in the disk. This enables us to follow the complete dust creation, avalanche and blow out processes in the disk. Understanding these collisional processes is very important since they strongly effect the properties, formation and evolution of planetary systems.

### Turbulent dissipation in the diffuse medium : its dynamics revealed by combined HIFI observations of 13CH+ and SH+

Proposal ID: OT2_bgodard_1

Principal Investigator: Benjamin Godard

Time: 14.7 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

Among all species detected in the diffuse interstellar medium, CH+ and SH+ are unique. Since their main production pathways are highly endo-energetic, their large observed abundances are likely the signature of the dissipation of turbulence. In addition, since the energies involved in their formation differ by more than a factor of 2, a comparative analysis of CH+ and SH+ provides essential clues on the nature of the dynamical processes involved in turbulent dissipation.

We propose here to perform sensitive Herschel/HIFI observations of 13CH+ and SH+ in absorption towards 5 background dust continuum sources located in the inner Galaxy : W49N, G34, W51, DR21(OH), and W33A. Each line-of-sight samples kiloparsecs of diffuse interstellar matter. Given the sensitivity and resolution of HIFI, we propose to reach a signal/noise ratio of about 300 in order to analyze the velocity structure of individual clouds along the sightlines. This project has two main goals : (1) characterize the kinematic signatures of the 13CH+ and SH+ absorption lines and compare them, statistically, to those of molecular species whose formation routes are less (or not) endothermic and (2) confront the 13CH+ and SH+ abundances to model predictions in order to directly derive for the first time the turbulent dissipation rate and the ion-neutral velocity drift driving dissipation in individual diffuse clouds.

### Brown Dwraf Disc Fraction at Ages of ~30-50 Myr

Proposal ID: OT2_briaz_5

Principal Investigator: Basmah Riaz

Time: 19.4 hours priority 2

Category: Circumstellar/Debris disks

Summary:

We propose to determine the brown dwarf disc fraction at ages of ~30-50 Myr. A comparison of the disc frequencies for stars and brown dwarfs shows very different trends with age. For the solar-type stars, optically thick primordial discs are virtually non-existent by an age of ~10 Myr. At ages >10 Myr, the inner disc material is significantly dissipated, and the discs have made a transition to the debris phase. In comparison, brown dwarf discs at ~10 Myr exhibit strong excess emission in the Spitzer/IRS 5-35µm spectrum, and also show strong excesses at Spitzer 70µm. The mid-infrared colors for these ~10 Myr old discs are found to be similar to the young optically thick discs in the ∼3 Myr old σ Orionis cluster, which indicates that these are still in their primordial phase. Thus no clear transition from a primordial to a debris phase is observed for the brown dwarf discs even at ∼10 Myr ages, unlike the higher mass stars. Furthermore, we find an increase in the brown dwarf disc frequency by a factor of ~2 between 5 and 10 Myr. We propose to observe with Herschel/PACS a sample of all spectroscopically conﬁrmed brown dwarfs in clusters at ages of ∼30-50 Myr. At present, PACS is the only instrument with the required high sensitivities to observe brown dwarf discs at these ages. Obtaining data for brown dwarfs at ages older than 10 Myr will be important to map the evolution of brown dwarf discs over a wider age range, and to determine if the brown dwarf disc decay time scale is longer than that observed for the earlier-type stars.

### Herschel Characterization of Dusty Debris Disks

Proposal ID: OT2_bzuckerm_2

Principal Investigator: Ben Zuckerman

Time: 10.7 hours priority 2

Category: Circumstellar/Debris disks

Summary:

We propose to measure with PACS and SPIRE the broadband fluxes of two partially overlapping classes of nearby main sequence stars. Each star possesses one or both of the following characteristics: (a) it is a member of a known nearby, young, moving group, and (b) it is known to have orbiting cool dust, but the dust has been seen at only one wavelength in the far-infrared -- either with IRAS at 60 microns or with Spitzer/MIPS at 70 microns – or only in the mid-IR with MIPS at 24 microns or with Spitzer/IRS. Therefore both the quantity and temperature of the dust particles are highly uncertain. Scientific motivation for the proposed observations include (1) improvement of our understanding of properties of debris disks at young main sequence stars, (2) provision of a set of relatively bright debris disks for study with ALMA, (3) provision of knowledge of the dust properties for stars with companions, regardless of whether the companion is stellar or planetary; in the case of planetary companions, many of our proposed Herschel target stars will be observed with the extreme adaptive optics systems SPHERE and/or GPI.

### A deep Herschel PACS imaging survey of transitional disks

Proposal ID: OT2_calvesde_1

Principal Investigator: Catarina Alves de Oliveira

Time: 22.2 hours priority 2

Category: Circumstellar/Debris disks

Summary:

We propose to observe with Herschel PACS a sample of 64 candidate transitional disks around young stars with the goal of characterising their disk geometry and relate it to the physical processes ruling disk evolution. The defining characteristic of transitional disks is a reduced opacity in the inner disk, indicating the onset of the disk dissipation phase and thought to represent an intermediate evolutionary state between primordial and debris disks. They constitute the last stage where gas and dust are available to form planets, and therefore their study is of extreme value in understanding planet formation including the formation of our own Solar System.

The sample of candidate transitional disks we propose to observe has been selected from a compilation of all the Class II young stellar objects members of nearby young clusters and associations, with known spectral types and spectral energy distributions complete up to the mid-IR. Our survey will greatly enrich the Herschel archive by extending current observations of transitional disks to a larger range of stellar masses, ages, and environments, as well as in sensitivity.

Using PACS photometry we aim at characterising the disk structure and geometry for this large sample of transitional disks, to study possible correlations of the disk parameters with their host star and environment. By combining Herschel data with complementary diagnostics (accretion rates, dust masses, multiplicity) we will determine the likely causes for disk clearing, to ultimately learn about the processes of disk evolution leading to planet formation.

This proposal is the last chance to acquire the far-IR information needed to fully exploit the scientific potential of our sample of candidate transitional disks in the coming decades. These objects are central to the understanding of disk evolution and the earliest stages of planet formation, and therefore the observations we propose have a high legacy value.

### Searching for the onset of energetic particle irradiation in Class 0 protostars

Proposal ID: OT2_cceccare_4

Principal Investigator: Cecilia Ceccarelli

Time: 19.6 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Several evidences tell us that the first stages of low mass star formation are very violent, characterized by, among other phenomena, an intense irradiation of energetic (MeV) particles. The goal of this proposal is to search for signs of MeV particle irradiation in a sample of low to intermediate mass Class 0 protostars. At this end, we propose to observe a selected list of high J HCO+ and N2H+ lines in a selected sample of sources. Based on the observations obtained within the KP CHESS, we estimate a total observing time of 20.5 hours.

### Peering into the engine of a jet-driven bowshock : TMC1B1

Proposal ID: OT2_cceccare_5

Principal Investigator: Cecilia Ceccarelli

Time: 5 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Jet-driven bowshocks seem to be rather ubiquitous in star-forming regions. If the large-scale bow is commonly observed and its kinematics, the actual engine of the outflow, the Mach disk region where the gas is accelerated, has never been detected until now.

Recently, we have found observational evidence of the long-searched engine of outflows in the giant molecular bowshock TMC1B1 together with the driving jet, in Taurus (d=140 pc).

which allows Herschel to resolve the cooling region of the shock. We propose to use Herschel to investigate the dynamics and physical structure of TMC1B1, a potential benchmark for jet-driven bowshocks studies.

### A Search for C II Around Dusty A-Type Stars

Proposal ID: OT2_cchen01_3

Principal Investigator: Christine Chen

Time: 7.3 hours priority 2

Category: Circumstellar/Debris disks

Summary:

We propose to obtain PACS C II 157.7 micon line spectra of 10 bright debris disks around dusty, A-type stars (with 70 micron fluxes >0.4 Jy) that are expected to be gas-rich if circumstellar gas in debris disks is generated via collisinal vaporization and/or photo desorption. C II is expected to be the dominant cooling line in debris disks. The high luminosity and UV flux of A-type stars is expected to efficiently produce second-generation gas. We plan to (1) constrain directly the gas:dust ratio in debris disks, (2) test models for the production of second-generation gas from circumstellar dust, and (3) extrapolate the composition of undetected parent bodies. Since the C II line emission from debris disks is relatively faint, PACS is required to conduct these observations

### Where is chlorine in shocked regions?

Proposal ID: OT2_ccodella_2

Principal Investigator: Claudio Codella

Time: 7.2 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

As part of the GT Herschel Program CHESS we detected for the first time hydrogen chlorine in a protostellar shock, L1157-B1 (Codella et al. 2011). One of the most surprising results of this work was the lack of enhancement in the abundance of HCl with respect to dense interstellar clouds, implying that HCl is not enhanced by the passage of a shock. This means that either chlorine is not sputtered during the passage of the shock (unlikely as Si is sputtered) or that HCl is not the main reservoir of clorine in shocked regions (unlike in dense interstellar clouds). In this proposal we propose to observe HCl in a sample of shocked regions in order to determine whether this result is unique to L1157-B1. We stress that given the weakness of the HCl emission in shocks and the strong atmospheric water absorption at the requested frequency (626 GHz), the present experiment cannot be reasonably performed from ground, making of Herschel OT2 the last chance to reach the present goals.

### Observations of a Sleeping Giant: A Herschel Survey of the California Molecular Cloud

Time: 25.2 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

We propose to use the Herschel telescope in the unique SPIRE/PACS parallel mode configuration to completely map the California Molecular Cloud in five photometric bands to the confusion limit at SPIRE submillimeter wavelengths. At a distance of 450 pc the California cloud rivals the famous Orion A cloud as the largest and most massive GMC in the solar neighborhood. However the California Molecular Cloud contains more than an order of magnitude fewer YSOs than Orion and is characterized by a star formation rate that is an order of magnitude lower than that in Orion. It is thus an ideal laboratory for studying the physical conditions that give rise to low rates of star formation in GMCs and thus for ultimately determining the physical factors that control the star formation rate in molecular gas, critical information required for understanding galaxy formation as well as star formation. The specific goals of this experiment are to: 1) identify and characterize the dense core population, 2) construct the core mass function (CMF) of the cloud, 3) obtain a more complete and accurate census of the YSO population and thus star formation rate in the cloud, and 4) accurately determine the nature and evolutionary status of the individual YSOs in the cloud via modeling of their SEDs. For this purpose the Herschel data will be combined with ancillary ground-based and space-based (Spitzer) photometric measurements following a method we successfully tested in a previous investigation of the natures of the NGC 2264 and IC 348 YSO populations. The proposed Herschel observations will be part of a coordinated, multi-wavelength campaign modelled on our highly successful study of the Pipe Nebula and will provide results that will constitute an important complement to those Herschel programs studying molecular clouds with rich star formation activity. So far, only about half of the California cloud is covered by planned Herschel observations, and we thus propose to complement and double the coverage of existing programs.

### Intermediate Mass YSOs: getting to the core of the matter

Proposal ID: OT2_cmccoey_2

Principal Investigator: Carolyn McCoey

Time: 6.3 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

Due to a dramatic increase in gas-phase abundance above temperatures of 100 K, water emission illuminates the important 'milestones' of star formation. Gravitational collapse, accretion shocks, protostellar heating of envelopes and disks, and the injection and motion of outflows into the protostellar envelope all glow in water. At the same time, water in absorption probes the conditions of the cold gas. Determination of water abundance throughout the envelope allows us to place strong constraints on the the physical structure of the envelope and energy transfer occurring within it.

Analysis of H2O and H2018O transitions observed with HIFI towards intermediate mass Young Stellar Objects have shown that, contrary to expectations, the ground state H2-18O line (547.676 GHz) does not trace the warm inner envelope. Test observations towards two of our sources have confirmed model predictions that the higher excitation line at 1095.627 GHz can be used to probe the warm inner envelope and hot core.

Following this result, we propose to observe the remaining intermediate mass YSOs on our source list. We request 12.3 hours to perform HIFI DBS observations in band 4b in order that we may determine the water abundance in the inner regions of these proto-stellar envelopes.

### Evolution of water emission in intermediate mass YSOs

Proposal ID: OT2_cmccoey_3

Principal Investigator: Carolyn McCoey

Time: 11.3 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

Intermediate mass YSOs are studied as part of the WISH KP. We find our source sample is too limited to identify properties associated with stellar evolution. With this proposal we ask for time to observe two more intermediate mass YSOs with HIFI and PACS.

When looking at line profiles among or source set a confused picture appears. NGC 7129 FIRS 2 and LDN 1641 are both Class 0 YSOs but have very different line profiles. Similarly, the Vela sources are both Class I sources and even have almost the same bolometric luminosity but display very different spectra. It is noteworthy that line profiles of the Class 0 NGC 7129 FIRS 2 are very similar to the line profiles of the Class I Vela IRS 17. Furthermore, the most evolved source, AFGL 490, is most similar, albeit brighter, to one of the least evolved sources, LDN 1641.

We require more observations in order to assess if there is any relation in line profile with evolutionary state. We ask for time to observe the Class 0 intermediate YSO, Cep E-mm, and the Class I/II sources, LkHa 224.

### Environmental impact on planetary systems in the rich alpha Per cluster

Proposal ID: OT2_cmelis_3

Principal Investigator: Carl Melis

Time: 2 hours priority 1

Category: Circumstellar/Debris disks

Summary:

The environment in which a star forms can potentially have a significant effect on the final planetary system that forms around it. We have recently carried out a WISE survey of the nearby, rich, young alpha Per cluster, a cluster essentially not observed with the Spitzer Space Telescope. Our findings suggest that this cluster is deficient in debris disks relative to other clusters in the same age range. We propose to use Herschel/PACS observations of WISE-detected alpha Per debris disks to determine if their distribution in semimajor axes is consistent with dynamical interactions as a principal cause of the low alpha Per debris disk fraction.

### PACS photometry of water-rich protoplanetary disks

Proposal ID: OT2_csalyk_2

Principal Investigator: Colette Salyk

Time: 2.9 hours priority 2

Category: Circumstellar/Debris disks

Summary:

A major breakthrough in addressing the connection between disks and planets occurred in 2008 with the Spitzer Space Telescope discovery of a forest of mid-infrared emission lines of water and other molecules emitted by a high percentage of protolanetary disks around young, low-mass stars. These molecular lines reflect the physical and chemical state of the disk, and can be used in concert with disk models to study disk physical and chemical diversity in greater detail than ever before. In particular, our team is mapping the distribution of water vapor, to determine where and when planetary cores condense, and searching for the reason behind observed chemical variations between disks. A major, but not insurmountable, difficulty in the interpretation of the molecular emission from disks is the significant degree of degeneracy in disk models. The way around this difficulty is to obtain detailed multi-wavelength datasets. The far-IR region is especially crucial, as the dust here transitions from optically thick to thin, and emission depends sensitively on the temperature and density structure of the dust. We therefore propose here to complete the census of PACS photometry for emission-rich disks.

### HIFI CO observations of protoplanetary disks with molecular winds

Proposal ID: OT2_csalyk_3

Principal Investigator: Colette Salyk

Time: 38.1 hours priority 2

Category: Circumstellar/Debris disks

Summary:

We propose to use HIFI to observe resolved CO rotational line emission from a newly-identified class of disks --- the disk wind'' sources. These disks have emerged as a possible link between disks with envelopes and large outflows, and older, exposed and quiescent disks, and as such offer exciting potential for new discoveries. Multiple lines of evidence suggest that these disks produce significant wide-angle molecular winds, distinct from the jet-driven outflows observed in younger sources, but the detailed structure of this wind, and its launching mechanism, remain unknown. We propose here to observe resolved CO 14-13 line profiles with HIFI from 2 disk wind sources and a reference classical disk, to provide information complementary to that provided by an extensive existing multi-wavelength dataset. In particular, high-excitation CO rotational lines, like CO 14-13, probe a distinct temperature and density regime in the disk and wind, sensitive to the few-10 AU region, which cannot be otherwise probed from ground-based observatories.

### Exploring the role of CII in current Spinning Dust Models

Proposal ID: OT2_ctibbs_1

Principal Investigator: Christopher Tibbs

Time: 14.9 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

We propose HIFI observations of the CII fine structure line at 158 micron (1.9THz) in 22 pointings distributed across four Galactic anomalous emission regions (the Perseus cloud, LDN 1780, LDN 675 and LDN 1111). The currently favoured explanation for the observed anomalous microwave emission is that of electric dipole radiation from rapidly rotating small dust grains (PAHs and/or VSGs), commonly referred to as spinning dust. Although this hypothesis predicts that the source of the excess emission is due to dust, the small dust grains are sensitive to the ionisation state of the gas, and hence the spinning dust models have a dependancy on the abundance of the major gas ions. CII observations will enable us to investigate this dependancy, and combining these observations with the available mid- to far-IR observations will permit a complete analysis of the role of both the dust and gas in regions of anomalous emission. We request a total of 14.9 hrs of HIFI observing time.

### PACS Photometry of Transiting-Planet Systems with Warm Debris Disks

Proposal ID: OT2_dardila_2

Principal Investigator: David Ardila

Time: 21.1 hours priority 1

Category: Circumstellar/Debris disks

Summary:

Dust in debris disks is produced by colliding or evaporating planetesimals, the remnant of the planet formation process. Warm dust disks, known by their emission at =<24 mic, are rare (4% of FGK main-sequence stars), and specially interesting because they trace material in the region likely to host terrestrial planets, where the dust has very short dynamical lifetimes. Dust in this region comes from very recent asteroidal collisions, migrating Kuiper Belt planetesimals, or migrating dust.

NASA's Kepler mission has just released a list of 1235 candidate transiting planets, and in parallel, the Wide-Field Infrared Survey Explorer (WISE) has just completed a sensitive all-sky mapping in the 3.4, 4.6, 12, and 22 micron bands. By cross-identifying the WISE sources with Kepler candidates as well as with other transiting planetary systems we have identified 21 transiting planet hosts with previously unknown warm debris disks.

We propose Herschel/PACS 100 and 160 micron photometry of this sample, to determine whether the warm dust in these systems represents stochastic outbursts of local dust production, or simply the Wien side of emission from a cold outer dust belt. These data will allow us to put constraints in the dust temperature and infrared luminosity of these systems, allowing them to be understood in the context of other debris disks and disk evolution theory.

This program represents a unique opportunity to exploit the synergy between three great space facilities: Herschel, Kepler, and WISE. The transiting planet sample hosts will remain among the most studied group of stars for the years to come, and our knowledge of their planetary architecture will remain incomplete if we do not understand the characteristics of their debris disks.

### Direct measurements of the warm gas distribution and vertical temperature gradient in protoplanetary disks.

Proposal ID: OT2_dfedele_2

Principal Investigator: Davide Fedele

Time: 14.4 hours priority 1

Category: Circumstellar/Debris disks

Summary:

Recent observations of protoplanetary disks with Herschel have revealed the presence of high-J CO lines. State-of-the-art disk models predicts that this emission arises from intermediate layers below the disk surface and above the mid-plane. These layers are shielded from the photodissociative (UV) radiation emitted by the pre-main-sequence star and are thus very important for the chemical evolution of the disk. Previous observations with PACS allows us to determine the temperature and density of the gas in these layers. The low-resolution spectra of PACS, however, does not provide direct information on the distribution of the gas. We propose follow-up observations with HIFI of the J=16-15 CO line previously detected with PACS in 8 disks. The high-spectral resolution of HIFI will allow us to directly measure the radial distribution of the emitting gas. This modest (14 hours) HIFI proposal will complement the previous PACS observations allowing to fully characterize the properties of the warm gas (temperature, density and radial distribution). The second goal of this project is to address the vertical temperature gradient inside the disk. This will be achieved by comparing the HIFI observation of CO J=16-15 line to spectrally-resolved ro-vibrational and low-J CO emission lines observed from the ground. For this we will implement thermo-chemical disk models developed in our group. We also propose follow-up HIFI observations of the strong [CII] emission detected with PACS in three protoplanetary disks. According to disk models this line is expected to emerge from the ionised disk surface of the disk and is linked to the CO chemistry (photodissociation). However, the measured line flux in HD 100546, HD 97048 and IRS 48 is high and might not all come from the disk but rather from an outflow or a remnant envelope. HIFI will allow to resolve to resolve the velocity profile of the line and in turn to disentangle its origin.

### Ammonia as a Tracer of the Earliest Stages of Star Formation

Proposal ID: OT2_dlis_3

Principal Investigator: Dariusz Lis

Time: 16.7 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Stars form in molecular cloud cores, cold and dense regions enshrouded by dust. The initiation of this process is among the least understood steps of star formation. High!resolution heterodyne spectroscopy provides invaluable information about the physical conditions (density, temperature), kinematics (infall, outflows), and chemistry of these regions. Classical molecular tracers, such CO, CS, and many other abundant gas!phase species, have been shown to freeze out onto dust grain mantles in pre!stellar cores. However, N!bearing species, in particular ammonia, are much less affected by depletion and are observed to stay in the gas phase at densities in excess of 1e6 cm!3. The molecular freeze!out has important consequences for the chemistry of dense gas. In particular, the depletion of abundant gas!phase species with heavy atoms drives up abundances of deuterated H3+ isotopologues, which in turn results in spectacular deuteration levels of molecules that do remain in the gas phase. Consequently, lines of deuterated N!bearing species, in particular the fundamental lines of ammonia isotopologues, having very high critical densities, are optimum tracers of innermost regions of dense cores. We propose to study the morphology, density structure and kinematics of cold and dense cloud cores, by mapping the spatial distribution of ammonia isotopologues in isolated dense pre!stellar cores using Herschel/HIFI. These observations provide optimum probes of the onset of star formation, as well as the physical processes that control gas!grain interaction, freeze!out, mantle ejection and deuteration. The sensitive, high!resolution spectra acquired within this program will be analyzed using sophisticated radiative transfer models and compared with outputs of state!of!the!art 3D MHD simulations and chemical models developed by the members of our team.

### High frequency water masers with Herschel/HIFI

Proposal ID: OT2_dneufeld_7

Principal Investigator: David Neufeld

Time: 10 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

Using HIFI, we will observe three rotational transitions of water vapor, all predicted to be strong submillimeter masers, toward the massive star-forming regions W49N and W51 (Main); and toward the oxygen-rich evolved stars VY CMa and U Her. The target transitions are the 5(23) - 4(41), 5(24) - 3(31), and 6(34) - 5(41) pure rotational lines of water at 621, 970, and 1158 GHz. In combination with maser transitions of lower frequency that can be observed from the ground, the proposed observations will constrain the conditions of gas temperature, gas density, and IR radiation field within the maser-emitting region, providing important constraints upon the maser pumping mechanism. In the case of the star-forming interstellar regions, the proposed observations will also constrain the nature of the shock waves that power the maser emission.

### Warm A Star Debris Disks from WISE

Time: 32.5 hours priority 2

Category: Circumstellar/Debris disks

Summary:

Debris disks trace the collisional breakdown of asteroid and comet parent bodies orbiting nearby main sequence stars. Debris disks are typically cold analogs of our Kuiper belt with emission peaking near 70 microns wavelength. However, a relatively small number of warm disks are known with emission at 22 - 24 microns. These systems are especially interesting because they trace dust in the region likely to host terrestrial planets, where the dust has a short dynamical lifetimes. They also tend to be young systems aged < 1 Gyr. This knowledge of warm debris disks - extrasolar analogs to our solar system's Zodiacal cloud - is based on the 25 year old IRAS survey and observations of selected targets with ISO and Spitzer.

The Wide-Field Infrared Survey Explorer (WISE) has recently completed new, sensitive all-sky mapping in the 3.3, 4.6, 12, and 22 micron bands. Association of the WISE sources to Hipparcos and Tycho stars has led to the identification of 61 nearby main sequence A stars with robustly detected warm 22 micron excesses not previously known. To determine whether these systems represent outbursts of asteroidal dust production (such as in the HD 69830 system), or simply the Wien side of emission from a cold outer dust belt, photometry at longer wavelengths is needed. We propose Herschel/PACS 70 and 160 micron photometry of this unbiased sample of new A star debris disks. These data will allow us to fully characterize the dust temperature and infrared luminosity of these systems, allowing them to be understood in the context of other debris disks and disk evolution theory. Herschel OT1 observations of FGKM stars from this survey show a 90% detection rate for 70 micron excess emission. The results from these combined samples will strongly constrain our picture of the collisional history of inner planetary systems.

### Unveiling the spectral shape of warm Galactic dust emission

Time: 15.4 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

The largest dust grains dominate the total dust mass, as well as the observed emission in the far-infrared (FIR) domain. They contribute to the efficient cooling in the FIR and submillimeter/millimeter (submm/mm) wavelengths, essential for the condensation of the ISM and the star formation process. Understanding the variations in dust emissivity is of primary importance, because they directly affect the accuracy of any mass determination using the Herschel photometric data. They are also extremely interesting in the prospect of understanding dust physics. For long time, the lack of data in the submm domain has induced to model the submm dust emission by a modified black-body, characterized by the mean dust temperature and a temperature and wavelength independent spectral index. However, analyses of recent data have shown a significant flattening of the dust emission spectrum in the submm/mm domain, for temperatures around 20 K. Emissivity variations also seem to be temperature-dependent. Two main models of the FIR/submm emission have been proposed to explain astrophysical observations, leading to different estimates of the interstellar medium characteristics. The present proposal aims at obtaining Herschel low resolution spectroscopic data towards the warmest regions of the ISM, in order to measure precisely their dust continuum emission. Indeed, dust processes occuring in warm/hot environments are poorly known. This unique combination of PACS and SPIRE spectroscopy for a sample of 7 compact/ultra-compact HII regions, accounting for 15.4h observing time, will allow us to efficently discrimate between possible dust models.

### Unveiling the water puzzle in cold PDRs: The Horsehead case

Proposal ID: OT2_dteyssie_2

Principal Investigator: David Teyssier

Time: 4.6 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

While Herschel observations of water vapour in warm regions (T_gas >> 100 K) driven by energetic processes (outfows, shocks, hot cores, etc.) have confirmed large abundances of water vapour (~10^-5), the inferred gas phase H2O abundance in dark clouds is very low, ~10^-10. A detailed balance between freeze-out, ice-mantle desorption and gas-phase chemistry is required to explain this orders-of-magnitude abundance difference.

The Horsehead nebula is particularly well-suited to investigate grain surface chemistry in a UV irradiated environment. Its relatively low UV illumination (~60 in Draine units) implies low dust grain temperatures, from T_dust=30K in the PDR to T_dust=20K deeper inside the cloud. Therefore, the release of the grain mantle products into the gas phase, water vapour in particular, is dominated by UV-induced photo-desorption and not by thermal evaporation (as in other warm PDRs such as the Orion Bar). Besides, owing to its simple edge-on geometry, the Horsehead is very close to the prototypical kind of source needed to serve as model benchmark.

A relatively low water vapour beam-averaged abundances (~5x10^-9) was derived from a single position of the o-H2O ground-state line towards the so-called "IR peak" of the Horsehead PDR. However a detailed comparison with sophisticated PDR models including gas and grain chemistry is not possible due to our complete ignorance about the true H2O spatial distribution as one moves from the UV-illuminated cloud surface to the inner shielded cloud. We propose here to map with HIFI the o-H2O 557 GHz line on a cut across the PDR front, and extract the spatial information required to constrain the role of water freeze-out and water ice photodesorption as a function of cloud depth.

### HIFI and SPIRE spectroscopy of HOPS 87: a bright water-rich protostar without an outflow

Proposal ID: OT2_dwatso02_5

Principal Investigator: Dan Watson

Time: 12.6 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

We propose to use Herschel HIFI and SPIRE to observe emission lines of water and CO in a low-mass Class 0 protostar, HOPS 87 (a.k.a. OMC-3 MMS 6N), for which we have characterized the water emission spectrum extensively with Spitzer-IRS and Herschel-PACS. HOPS 87 is the most luminous source of water emission lines found in a survey of low-mass YSOs, but has very little other emission that could be taken as evidence of a high-velocity outflow; if it truly lacks such an outflow at present it provides a rare opportunity to examine emission from the infalling envelope and potentially the envelope-disk accretion shock. With HIFI spectra we will determine whether or not the water emission arises in a high-velocity outflow, and detect separately the kinematic signatures of the warm inner envelope, the outflow-cavity walls, and perhaps the envelope-disk accretion flow. Confirmation of the detection of dense water in the disk accretion flow, which has been suggested as the origin of the mid-infrared (20-40~\micron ) water emission, would be the first unambiguous detection of this flow and is a major goal of this proposal. With SPIRE spectra we will complete our Spitzer-IRS and Herschel-PACS census of water and CO emission in this object, thereby obtaining a particularly complete and detailed account of physical conditions in the HOPS 87 envelope.

### H3O+ as a tracer of Galactic Center Black Hole activity

Proposal ID: OT2_ebergin_6

Principal Investigator: Edwin Bergin

Time: 16 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

The center of the Milky Way harbors a now dormant massive black hole (Sgr A*). Over the years evidence has mounted that Sgr A* released an energetic X-ray flare nearly 100 years ago. The strongest evidence for this is the detection of reflected X-ray emission towards molecular clouds in the central regions of the galaxy. We believe that we have directed direct evidence of the effects of this flare due to the presence of warm (excitation termperature ~ 600-800 K) H3O+ in the envelope of the Sgr B2 molecular cloud. These observations were obtained as part of the HEXOS key program and in all we have detected H3O+ J,K = 1,1 through 11,11 each in absorption. These are the inversion transitions that lie at the bottom of a given K ladder. For J,K > 3 the transitions cannot be be excited by conventional collisional excitation or by radiative pumping. Instead our model strongly favors that the rotationally warm H3O+ is the result of formation pumping due to the strong impinging X-ray flux, potentially from Sgr A*. We propose to follow up this fantastic result with a small search for rotationally warm H3O+ absorption towards other galactic center molecular clouds that are strong continuum sources and are in close proximity to Sgr A*. This proposal follows a very interesting molecular astrophysical puzzle that may be a direct link to activity from the central engine of our galaxy.

### Low gas to dust ratio in protoplanetary disks: the Carbon content of CQ Tau MWC 758 and MWC 480

Proposal ID: OT2_echapill_2

Principal Investigator: Edwige chapillon

Time: 5.3 hours priority 1

Category: Circumstellar/Debris disks

Summary:

The study of the transition from gas−rich protoplanetary disk to gas−poor debris disk is crucial to constrain the planetary formation mechanisms. Although it is a key parameter for big gaseous planet formation, the evolution of the gas−to−dust ratio with time and star properties is not yet known. One of the first steps to observationally constrain it is to determine independently the gas mass and the dust mass of disks. The dust content, determined from continuum emission, is better known than the gas content. As molecular hydrogen is not observable at the low temperatures of disks, the gas mass is usually derived from CO observation. However, CO may not be always the main carbon reservoir: it should freeze on grain mantles in the cold mid−plane of T Tauri disks, and be photodissociated in the upper layers by the UV field, leading to CI and CII, especially in disks surrounding A stars. We propose here to characterize the gaseous Carbon content in three disks (CQ Tau, MWC 758 and MWC 480) using the three main C carriers: CO, CI and C+. Previous CO observations indicates warm disks (the temperature being well above the CO freeze−out temperature). Two of them, CQ Tau and MWC 758, have very low CO content and may be in the transition stage between gas−rich and gas poor disks. A low CI content was also found for CQ Tau using APEX. We propose to take advantage of sensitivity of Hershel at 1900 GHz (157 um) and high spectral resolution provided by the HIFI instrument to observe C+ in these disks.

This proposal was ranked B for the OT1 period. We resubmit an updated version.

### The Herschel/HIFI insight on the CH+ puzzle in the diffuse medium

Proposal ID: OT2_efalgaro_2

Principal Investigator: Edith Falgarone

Time: 11.3 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

Seventy years after its discovery in the diffuse interstellar medium, the origin of the CH+ cation is still elusive. Herschel/HIFI offers a unique opportunity to disclose the underlying gas dynamics at the origin of CH+ in the diffuse medium by allowing high sensitivity and high spectral resolution observations of the CH+(J=1-0) transition, unreachable from the ground: it is the only instrument, for the decades to come, able to bring a completely new look at this resilient puzzle.

The abundant CH+ ion is not only a sensitive tracer of the most tenuous phases of the interstellar medium but it appears as a specific tracer of turbulent dissipation, because its formation route is highly endoenergic. We propose absorption spectroscopy observations of the CH+ J=1-0 line, against 7 background dust continuum sources, bright enough to allow the sample Galactic environments with highly different turbulent dissipation rates. We take advantage of the high opacity of the CH+(1-0) transition to search for CH+ in more diffuse components than previously observed: in the high-latitude diffuse medium, in gas out of the Galactic disk and in the outer Galaxy. The unknown H2 molecular fraction of these poorly explored parts of the diffuse Galactic component will be inferred from the CH absorption lines.

The primarily goal of this project is the comparison of the CH+ abundances with model predictions, in which turbulent dissipation proceeds either in low-velocity shocks or intense velocity-shears. Another goal is testing the possibility that CH+ forms at the turbulent interface between the two thermally stable phases of the interstellar medium. Last, as HF, CH+ is a potential sensitive tracer of diffuse molecular matter in the early universe. Understanding its origin and the dissipative processes that it traces will shed a new light on galaxy formation and evolution.

### Unveiling the origin and excitation mechanisms of the warm CO OH and CH+

Proposal ID: OT2_ehabart_4

Principal Investigator: Emilie Habart

Time: 12.7 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

Photon Dominated Regions (PDRs), where physics and chemistry are driven by FUV photons, show an extreme rich warm gas photochemistry closely related to proto-planetary disks and starburst galaxies. Spatially resolved studies of nearby PDRs are essential as they enable us to characterise the physico-chemical processes that control the regions and can serve as templates for compact systems where these process cannot be disentangled. The rotationally excited lines of CO, OH and CH+ probe the warmest PDR gas layers, providing strong constrains for the modelling of both the complex physics and chemistry driven in the presence of FUV fields. The emission of these lines have been recently connected to the presence of high-density structures (clumps or filaments). We propose to map the high-J CO, OH and CH+ lines in the Orion Bar, using fully sampled PACS maps and HIFI observations. These observations will probe the spatial thickness of the line emission layers necessary for detailed comparison with the state of the art PDR models. This will enable us to characterize the origin and excitation mechanism of these high rotational lines improving our understanding of the physics and chemistry of the warm phase in the ISM.

### Characterisation of the Extended Gas Components in Protostars with Herschel

Proposal ID: OT2_epuga_1

Principal Investigator: Elena Puga

Time: 23.4 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

This proposal aims at investigating the early protostellar evolutionary phases of protostars. In addition to the study of their fundamental properties (e.g. density, temperature, infall rate, accretion rate), a major focus of this proposal is the interpretation of the more extended gas components connected to the protostar. Extended envelopes, outflow shocks and jets and PDRs originating in the outflow cavities can potentially ontribute to this complex more extended emission. The spatial discrimination between these different excitation mechamisms and the quiescent underlying gas requires the combination of spatial and spectral information on several diagnostics that span a range of physical and chemical conditions. We propose PACS full SED oversampled spectral mapping around a carefully selected sample of 7 protostars at different evolutionary stages in the Chamaeleon-Musca cloud complex. This region is particularly suited to spatially resolved studies due to its proximity. This proposal is one of the many spin-off projects with an origin in the Gould Belt Key Programme and will complement other Herschel studies of protostars.

### Water In Low-mass protostars: the William Herschel line Legacy (WILL)

Proposal ID: OT2_evandish_4

Principal Investigator: Ewine van Dishoeck

Time: 133.6 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

We propose a survey of water lines toward an unbiased flux limited sample of low-mass protostars newly discovered in recent Spitzer and Herschel Gould Belt imaging surveys. Water has long been speculated to be a key molecule in the chemistry and physics of star-forming regions, but its actual role is only now starting to emerge thanks to Herschel. Initial HIFI data reveal surprisingly complex water emission profiles, which uniquely trace the different dynamical processes during the embedded phase of star formation (outflows, jets, shocks, infall, expansion). By using lines originating from different energy levels, the water abundance in the cold and warm gas can be determined as function of velocity and thus the chemical processes that shape them (gas-grain interactions, high temperature reactions). The ortho/para and HDO/H2O ratios hold important clues on the temperature history of the clouds and on the journey of water from cores to disks and planets. Combination with PACS data on water and related species (O, OH, CO) can determine the total gas cooling budget and can quantify the 'feedback' of the protostar on its surroundings in terms of UV radiation and shocks.

The unbiased WILL sample allows all of these questions to be studied as function of source characteristics and protostellar evolution in a statistically significant way, thus charting the processes that shape the emerging young star and disk in the critical period from the collapse phase to the envelope dispersion stage. No other space-based heterodyne mission will be available to provide velocity resolved water lines for at least 30 years, making this program a true Herschel Gould Belt line emission legacy.

### Depletion Cores - the O2 Hideout?

Proposal ID: OT2_ewirst01_1

Principal Investigator: Eva Wirstroem

Time: 3 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

Molecular oxygen has proven to be the most elusive molecule in the interstellar medium. Despite the fact that it in theory forms easily in both warm and cold dense gas, extensive searches with SWAS, Odin and Herschel have only resulted in detections in two sources. In addition, upper limits in various astronomical environments are at levels of 1000 times less abundant than predicted by chemical models.

This situation requires either for atomic carbon to be abundant enough to suppress the O2 by CO formation, or for atomic oxygen to accrete onto grains and remain bound there. However, the binding energies of atoms to grains are highly uncertain and high abundances of OI in depleted gas have both been directly observed and inferred from observations of other molecules. A possible explanation is that OI is bound to grains by fixing (get hydrogenated to form ices) rather than sticking (van der Waals bonding to the surface potential), which will become less efficient in high density gas.

Based on this, our calculations show that molecular oxygen could be abundant in dense cores of high CO depletion. To test this theory, we propose to search a small sample of starless depletion cores for emission in the low excitation O2 line at 487.249~GHz using Herschel HIFI.

### Determining the Ice Desorption Mechanism in Cold Molecular Clouds

Proposal ID: OT2_ewirst01_2

Principal Investigator: Eva Wirstroem

Time: 1.6 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

Interstellar ices are readily formed from accretion of atoms and molecules onto cold dust grains, and in dense cores the gas would be depleted in all heavy molecules were it not for the operation of some non-thermal desorption process.

Methanol molecules are only formed efficiently from hydrogenation of CO molecules accreted onto grains, but is still widely observed in cold dense clouds. This attests to the operation of desorption processes not related to the heating up of the gas from a nearby star. Proposed mechanisms for injecting the ice mantle molecules into the gas-phase includes both continuous processes, such as cosmic-ray impacts, photodesorption, or ejection upon formation, and more transient ones such as clump-clump collisions, and effects of embedded protostars influencing the chemistry through shocks or dissipation of magnetohydrodynamic (MHD) waves. The presence of distinct peaks of methanol emission at positions significantly offset from protostars, however, implies that the desorption process is indeed transient, and likely to also disrupt a major part of the ice mantles. This would lead to very high water abundances at these peaks, clearly distinguishable from what is expected from photodesorption or steady-state gas-phase chemistry.

In order to constrain the active ice desorption mechanisms in cold molecular clouds, we thus propose to use HIFI to observe the ground state transition of ortho water at three different methanol peaks: two at different distances from the Class I protostar Barnard 5 IRS1, and one in L1512, a region free from protostellar activity.

### Do Debris Disks With Warm Dust Have A Cold Origin?--Searching For The Outer Planetesimal Belts

Proposal ID: OT2_fmorales_2

Principal Investigator: Farisa Morales

Time: 34.5 hours priority 1

Category: Circumstellar/Debris disks

Summary:

We propose Herschel dual-band PACS photometry for a unique set of 31 (B8—K0) stars that host on-going activity in the terrestrial planet zones, to probe for signatures of cold/outer planetesimal belts. We are interested in probing a fundamental question about planetary systems–is a two-belt structure like that of the solar system the most common outcome of planet formation? These young solar- and A-type have dust emission well characterized with Spitzer/IRS 5-35 micron spectroscopy, revealing dust regions similar in temperature to our asteroid belt and the interior zodiacal cloud (T∼150–200 K). Because the warm belts have a median temperature of ∼190K, slightly warmer than that expected at the snow line, we have reason to believe that there is a common grain creation mechanism operating in the inner regions of the star-disk systems. Herschel provides the observational sensitivity at PACS 70 (or 100) micron required to successfully constrain the extent of the inner/warm dust emission, or reveal the presence of an outer/colder belt of planetesimals. In summary, the PACS observations will: 1) detect the long wavelength emission of the warm/inner dust and/or establish the existence of an outer/colder planetesimal belt; 2) constrain via modeling properties of the emitting dust; e.g. charateristic temperature, minimum mass and position; 3) facilitate comparison of dust distributions across stellar spectral range; and 4) establish the overall architecture of the circumstellar dust, perhaps pointing to favorable regions where exoplanets may reside. We request 35.2 hours in PACS AORs using the mini-scan map mode for point-sources, selecting the blue (60–85 micron) ﬁlter for most (26 of 31) targets, and the green (85–125 micron) ﬁlter for 5 targets with Spitzer 70 micron detections in agreement with the short-wavelength warm-ﬁt extrapolations.

### Constraining the Long Wavelength Emission of Two-Belt Debris Disks

Proposal ID: OT2_fmorales_3

Principal Investigator: Farisa Morales

Time: 8 hours priority 1

Category: Circumstellar/Debris disks

Summary:

We propose Herschel dual-band PACS photometry for a unique set of 20 stars that host on-going activity in the terrestrial planet zones and evidence of an outer/colder dust component, to continue the exploration, begun with Spitzer, of their disk structure and composition. The 20 solar- and A-type stars in this sample have combined Spitzer IRS+MIPS (5 to 70 µm) SEDs suggesting a two-ring disk architectures that mirror that of the asteroidal-Kuiper belt geometry of our own solar system. However, the extents of the outer zones are unconstrained due to the lack of data beyond 70 µm. Also, because the warm belts in our sample—across the B8 thru K0 stellar spectral range—have a median dust temperature of ∼190 K, slightly warmer than that expected at the snow line, we have reason to believe that there is a common grain creation mechanism operating in the inner regions of the star-disk systems, perhaps related to icy planetesimals in a cold outer regions. Herschel provides the observational sensitivity at PACS 100 and 160 µm required to successfully constrain the long wavelength emission of the outer/cold disks, and possibly resolve a subset of them. In summary, the PACS observations will: 1) establish the characteristic dust temperature of the outer/cold belts and constrain the minimum mass and position of the debris rings; 2) possibly resolve the spatial extend of a subset of systems; 3) advance our understanding of dust particle composition by constraining the long wavelength emission; 4) facilitate comparison of dust distributions across stellar spectral range; and 5) establish the overall architecture of the circumstellar dust, perhaps pointing to favorable regions where exoplanets may reside. We request 8.0 hours total in PACS AORs using the mini-scan map mode for point-sources, selecting the green (85–125 µm) and red (125-210 µm) ﬁlters to constrain the long wavelength emission for all targets.

### Spatial distribution of HF emission in photon-dominated regions

Proposal ID: OT2_fvandert_1

Principal Investigator: Floris van der Tak

Time: 1.5 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

The HF molecule is an excellent tracer of H2, even at low column densities where CO is photodissociated, as shown by widespread absorption in the 1--0 line at 1232 GHz seen with Herschel. We have made the surprising observation that this line appears in emission towards the Orion Bar, which is where ultraviolet radiation from the Trapezium stars hits the molecular cloud and causes heating and dissociation. Three mechanisms may cause this unusual effect: thermal excitation, which requires very high gas densities; radiative pumping by dust continuum or H2 line emission at ~2.5 microns; or chemical pumping where most HF is formed in the J=1 state. These models each predict a distinct spatial distribution of HF, which is why we hereby propose one-dimensional maps of HF in the Orion Bar and two similar regions. Combined with existing maps of CO and dust emission, the new data will constrain the density structure of molecular clouds in the low column density regime which is inaccessible to other telescopes, and thus offer fundamental insight into the physics of the interstellar medium.

### A Water survey of massive star forming clumps in the inner Galaxy

Proposal ID: OT2_fwyrowsk_3

Principal Investigator: Friedrich Wyrowski

Time: 30.6 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

Water, as a dominant form of oxygen, the most abundant element in the universe after H and He, controls the chemistry of many other species. It is a unique diagnostic of warm gas and energetic processes taking place during star formation.

We therefore propose to exploit the unique opportunity of Herschel to study water in large, statistically significant, flux limited samples of massive star forming regions detected in the recently completed ATLASGAL submm dust continuum survey of the inner Galactic plane.

In the last years, our view of massive star forming regions has dramatically changed by Galactic plane surveys covering cm to IR wavelengths. These surveys enable us for the first time to study ALL evolutionary stages of massive star formation (MSF) in an unbiased way. Water, acting as a natural filter for warm, dense gas, allows to probe the chemical and physical conditions in all of these stages close to where the massive stars are forming or just have been formed.

ATLASGAL observed submm dust continuum emission as best tracer of the earliest phases of MSF since it is directly probing the material from which the stars form. As a large unbiased survey it provide the statistical base to study the scarce and short-living protoclusters as the origin of the massive stars and the richest clusters in the Galaxy and supplies us with a legacy value sample of MSF regions for the water follow ups.

Water is typically seen with strongly increased abundances in broad line wings, providing a new, sensitive probe of shocked outflowing gas. In addition, the envelope is probed in a combination of absorption and emission with a clear jump in abundance in the warm inner regions close to the forming massive stars. Only Herschel can provide a water survey of a large sample of ATLASGAL selected sources to study water through the evolution of massive star forming regions with a statistically significant sample size.

### Debris Disks around Low-Mass Planet-Bearing Stars

Proposal ID: OT2_gbryden_2

Principal Investigator: Geoffrey Bryden

Time: 17.1 hours priority 1

Category: Circumstellar/Debris disks

Summary:

Follow-up Herschel observations have recently confirmed the presence of a resolved debris disk around GJ 581, a nearby M star with 4 low-mass (super-Earth) planets. Debris disks around M stars are exceedingly rare (~1% detection rate in the DEBRIS survey), raising the question of whether the debris might somehow be directly related to the neighboring planets. In order to assess whether low-mass planets are strongly correlated with dusty debris or whether this is just a chance coincidence, we propose to dramatically increase the number of planet-bearing M stars observed by Herschel, from the current 3 up to a total of 20 stars. The proposed PACS 100/160 um images of 17 planet-bearing M stars will clarify whether this class of system preferentially has orbiting debris. Should any new disks be detected, the close proximity of the target M stars (~10 pc) makes them favorable candidates for resolved imaging, which may help to explain the unusual asymmetry in GJ 581's similarly resolved disk.

### A novel search for episodic accretion onto the youngest protostars

Proposal ID: OT2_gherczeg_2

Principal Investigator: Greg Herczeg

Time: 19 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

We propose to use second epoch PACS+SPIRE photometry of nearby star-forming regions to detect episodic accretion events onto the youngest, Class 0, protostars. It is well accepted that the bolometric luminosities of these young protostars fall at least an order of magnitude below the steady-state accretion luminosities needed for their assemblage and that as much as 90% of the total mass must be accreted during episodic events. Optical and IR monitoring of older, non-shrouded pre-main sequence stars has revealed powerful episodic events (FUors and EXors) but not until Herschel have we been able to map large enough star-forming regions to the depths necessary to perform this time-domain survey for episodic accretion onto Class 0 protostars.

The proposed 21.8 hour survey of Aquila, NGC 1333, Oph L1688, and IC 5146 will map more than 200 known Class 0 protostars, 500 Class I protostars, and thousands of pre-stellar cores. These second epoch multi-wavelength observations allow us to be sensitive to order unity variations in bolometric luminosity (and temperature) and thus while we are unlikely to observe any rare, extreme accretion events, we will be able to place constraints on the importance of more common accretion enhancements in supplying mass to the protostar. All interesting detections will become prime candidates for follow-up detection from the ground.

Our proposed Herschel program is our best chance to probe accretion variability for the youngest protostars, which are in an evolutionary stage that has not been observable in previous or ongoing variability surveys.

### A PACS Spectroscopic Survey of the Chemistry of Transition Disks

Proposal ID: OT2_gherczeg_4

Principal Investigator: Greg Herczeg

Time: 26.4 hours priority 2

Category: Circumstellar/Debris disks

Summary:

In the past decade, transition disks have emerged as the first possible, measurable signposts of planets that have already or are in the process of forming. Recent detections of planetary mass objects within the inner holes of two transition disks definitively link the presence of disk holes with planet formation. However, these transitional disks have so far not yet been studied much in the warm molecular gas of a few 100 K, which connects the cold bulk mass of the outer disk (probed in the sub-mm) with warm inner regions (probed in the near-IR). The structure of transition disks is typically measured from the shape of the spectral energy distribution or the spatially imaged dust. Although the gaseous disk can be more difficult to study, the structure and chemistry of gas will provide significant constraints on the prospects for the final abundances and continued growth of gas giant planets. Herschel PACS offers a unique possibility to study the mid-J to high-J lines of CO together with lines of OH and water. These lines are predicted to emerge from the inner few tens of AU. Here we propose a deep search for molecular emission in PACS spectra of 12 of the most exciting transitional disks, two of which are already approved for ALMA observations. These PACS observations provide diagnostic information on the structure and chemistry of the warm gas that is needed to constrain models of gas in transition disks and to understand the connections, if any, between the gas in the inner and outer disk.

### Debris Disks as a Tracer of Star and Planet Formation in Binaries

Proposal ID: OT2_gkennedy_2

Principal Investigator: Grant Kennedy

Time: 11.4 hours priority 1

Category: Circumstellar/Debris disks

Summary:

We propose to observe nearby binary star systems to discover and characterise circumbinary debris disks. With these data we will study the effects of cluster evolution and long term stability on planet formation. The primary goal is to resolve disks, which allows an analysis of the binary and disk orbital planes and leads to conclusions about the formation and stability of the system. The secondary goal is to test whether dust resides in unstable regions, which could be the result of a dynamical instability induced by perturbations from the binary. Both goals focus on the dynamics of circumbinary debris, and provide information on planet formation and survival in binary systems.

### Testing the Water Predictions of Thermo-Chemical Models of Externally-Illuminated Molecular Gas

Proposal ID: OT2_gmelnick_2

Principal Investigator: G.J. Melnick

Time: 8.8 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

Models that include the key radiative and chemical processes necessary to understand the emission from externally-illuminated molecular gas - so called thermo-chemical or PDR models - are now commonly invoked to account for the line flux from far-ultraviolet illuminated galactic and extragalactic molecular clouds as well as protoplanetary disk surfaces irradiated by their central stars. Whether these models are correct in general, and for water in particular, remains an open question; using present observations to test these models has proven difficult because of the complexity of the regions observed and the resulting uncertainty in many of the model input parameters. Using HIFI, we will obtain scan maps in the ground-state 1(10)-1(01) ortho-water transition at 557 GHz across the ionization front/molecular cloud interface toward two well-studied, uncomplicated regions with favorable geometry - Cepheus B and the starless dark globule DC 267.4-7.5. The proposed observations will produce measures of the gas-phase water abundance across these two atomic-to-molecular transition zones, which will be compared to the model-predicted profiles of water emission versus Av into the clouds. Because of the edge-on geometry and the absence of known embedded sources along the scan paths, the proposed observations provide the best, most controlled test of these models to date. Both regions have been successfully observed previously with SWAS, but SWAS's much larger beam size made the kind of study proposed here impossible. Neither the Herschel WISH nor PRISMAS Key Programs contains observations that come close to offering as rigorous a test of the models as constructed here. Because these observations require a space-borne telescope with both high spatial and spectral resolution, they cannot be carried out from any other observatory in the foreseeable future.

### Disk evolution in a cluster environment - PACS and SPIRE imaging of the LkHa198/V367 Cas region

Proposal ID: OT2_gsandell_1

Principal Investigator: Goeran Sandell

Time: 1.5 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

We will do sensitive PACS and SPIRE observations of the LkHa198/V376 cluster to find all young stars, determine their disk/envelope masses and the star formation rate in the cloud.

### Solving the puzzle of water excitation in shocks

Proposal ID: OT2_gsantang_1

Principal Investigator: Gina Santangelo

Time: 19.6 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Water is a highly complementary diagnostic to the commonly used CO molecule. It has a central role in protostellar environments and in outflow shocks, being one of the main coolants and the most sensitive to local conditions. As part of the WISH key program, a survey of several H2O lines at different excitation has been performed with HIFI at two selected shock spots in the bright L1448 and L1157 outflows. These observations and their analysis have given unexpected results, that contrast with current models of water emission in shocks. However, the validity of these results needs to be checked with suited high S/N observations, allowing to remove some of the free-parameters of the line excitation modeling and to derive water abundance.

The goal of this proposal is to clarify the controversial issues raised by these previous observations by mapping with HIFI a 40 arcsec area covering two shock positions along the NGC1333-IRAS4A outflow, identified as very bright in H2O from our PACS map at 1670 GHz, in key spectral transitions of H2O and CO. These observations will provide unprecedented constraints on the physical and chemical properties of the gas associated with the water emission, as a function of velocity, and on the properties of the shock at the origin of the emission. In particular, mapping the H2O lines will allow us to remove the uncertainty originated by the largely different beams of the observed transitions. The CO(16-15) will be also observed: this line comes from the same high excitation gas as that traced by H2O and thus will provide a tool to derive an H2O/CO abundance ratio much more reliable than what is obtained with the low-J CO transitions observed from ground.

We point out that it is crucial to solve the issue of water excitation in shocks before the end of the Herschel mission, in order to correctly interpret all the data acquired on H2O in outflows by Herschel and provide reliable constraints on water abundances and shock dynamics.

### Star Formation Within the Giant HII Region W80: Measuring SEDs and Mapping the Morphology of the North American Pelican and Gulf of Mexico Complexes

Proposal ID: OT2_gstringf_2

Principal Investigator: Guy Stringfellow

Time: 6.8 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

We propose to obtain a contiguous 5.3 square degree square map of the extended HII region W80 using PACS and SPIRE. Contained in this field of view are the little studied North American and Pelican nebulae, and a dark molecular cloud region referred to as the Gulf of Mexico. This region has not been globally mapped by Herschel. The distance to W80 (and regions therein) is about 600 pc making it the next nearest region similar to Orion. 2MASS extinction mapping reveals Av>5 mag over most of W80, and cores in several areas exceed 30 mag. Spitzer IRAC and MIPS have observed this entire complex, yielding catalogues of hundreds of potential YSOs. We have conducted a wide-field H2 2.12 micron partial survey for shocks and outflows and have discovered dozens of highly embedded energetic protostellar outflows and jets distributed over the cloud complexes. The region rivals NGC 1333 known to harbor the highest concentration outflow sources. The O-stars that produce the ionizing UV radiation and these new young, accreting sources are responsible for the intra-cloud dispersal and the triggering of star formation in surrounding regions. Herschel photometry at 5 bands (70, 160, 250, 350, and 500 microns) are required to complete the measurement of the SEDs thereby allowing classification, measure the temperature and masses of the disks, and to better define the extended structure and morphology of the intra-cloud medium, including IRDCs, pillars, and filaments. Herschel is vastly superior to mapping large scale structure of the cold dust, warm edges, and hot dust associated with PDRs, compared with mm-surveys (eg., ATLASGAL and BGPS) as these latter surveys tend to spatially filter out large scale structure >7' in their data processing. Herschel will provide the essential high angular resolution and sensitivity data needed to quantify each SED and to map the morphology of the complexes.

### Formation signatures and carbon budget of molecular clouds

Proposal ID: OT2_hbeuther_4

Principal Investigator: Henrik Beuther

Time: 19.3 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

The interstellar medium (ISM) is mainly comprised of ionized, neutral atomic and molecular gas. One of the most important constituents of these phases is carbon in its ionized/neutral/molecular form (C^+, C^0 and CO). However, a coherent analysis of the different phases at adequate resolution (Jeans length ~0.2pc) is lacking. We therefore want to re-evaluate the ISM carbon budget via observing primarily C^+ at 1.9THz, C^0 (at 492GHz), and CO(2-1) with Herschel, APEX and the IRAM 30m at high spatial resolution (11''-13'') for several infrared dark clouds (IRDCs). This proposal is a follow-up of a guaranteed time pilot study for the line of ionized carbon [CII] toward one IRDC. In this open time project we like to extend the sample to a total of five IRDCs in different environments. With the combined data of the different carbon phases we can address: (a) How do the relative abundances change with evolutionary stage? (b) Are the different phases mainly excited by internal or external radiation sources? (c) How important are the phase changes for the carbon cooling budget of the ISM? (d) Can we identify cloud formation signatures (e.g., turbulent flows)?

### A Deep Search for the Molecular Anions CN$^-$ CCH$^-$ OH$^-$ and SH$^-$ in the Galaxy

Proposal ID: OT2_hgupta_2

Principal Investigator: Harshal Gupta

Time: 13 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

We propose a sensitive search towards six Galactic sources for the small negative molecular ions (anions) --- CN$^-$, CCH$^-$, OH$^-$, and SH$^-$ --- with {\it Herschel's} Heterodyne Instrument for the Far-Infrared (HIFI). The full significance of anions in astrophysics is far from understood, and molecular anions may have a much broader impact on the chemistry and physics of astronomical sources than is currently appreciated. In dark clouds and low-mass star-forming regions, reactions of molecular anions are thought to enhance the abundances of neutral polyynes and cyanopolyynes. In circumstellar shells of evolved carbon stars, anions are theorized to form by proton transfer reactions of neutral carbon chain radicals with H$^-$, as well as through reactions of atomic N with large carbon chain anions. By influencing the ambipolar diffusion rate, anions may regulate the dynamics of star formation in magnetized plasmas around collapsing molecular cloud cores. Because the abundances of anions are sensitive to electron attachment and photodetachment rates, anions can serve as direct probes of electron densities and cosmic-ray ionization and photoionization rates within interstellar clouds, provided the formation and destruction processes of anions are known. The main question we seek to address is just how widespread anions are in the Galaxy. The four anions we propose to study are structurally simple molecules, with precursors that are abundant in the interstellar gas. The observations here will provide key information on the distribution small molecular anions, which, when combined with chemical models of the observed anion abundances and their dependence on conditions within their astrophysical environments, will advance our understanding of the role of anions in the physics and chemistry ofastronomical sources.

### Far-infrared spectroscopic imaging study of interstellar material around eta Carinae

Proposal ID: OT2_hmatsu01_2

Principal Investigator: Hiroshi Matsuo

Time: 7.8 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

Our science goal is to study the influence of massive star-forming　activities to the physical and chemical conditions of interstellar space. Our target region in the Carinae Nebula especially region around Eta　Carinae, where massive star clusters and molecular cloud complexes are observed and there are indication of past activities of stellar wind and current activities of star formation is observed. We use far-infrared atomic fine structure lines as a tool to study the influence of massive star to the interstellar material surrounding it. Observing area is selected from wide area spectroscopic imaging of　AKARI observations. Herschel Space Observatory will show the high angular resolution images of the selected regions with high activities. Eta Carina and their surroundings are at relatively low extinction region, and comparative study in X-ray, optical, infrared and radio observations can be done easily. Detailed observation of massive star forming region in Carina Nebula is important to understand the role of massive star-forming region in general in our galaxies and external galaxies including high extinction regions.

### HIFI Observations of Cold Cores in Infrared Dark Clouds

Proposal ID: OT2_hsmith_2

Principal Investigator: Howard Smith

Time: 20.9 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Infrared Dark Clouds (IRDCs) are thought to host the earliest stages of high-mass star formation, an epoch that is still poorly understood. Gound-based millimeter observations have found that many IRDCs have embedded cores, and Herschel PACS and SPIRE photometry has made it possible to image many of these very cold cores via their dust emission. We have used the Submillimeter Array (230GHz) to observed a sample of cold IRDCs that are dark even at PACS70, but which contain bright cores seen in emission in the SPIRE bands. The SMA spectral maps and the molecular chemistry suggest at least three early stages of star formation that we have tentatively modeled as reflecting three progressive temperature and evolutionary stages. Unfortunately in the youngest, coldest sources most diagnostic molecules are either frozen out onto grains or have not yet assembled. Nitrogen hydrides, however, do not suffer from depletion effects in cold, dense regions, and so offer an invaluable tool to probe the early stages. Herschel HIFI is uniquely suited to observe the key ground-state absorption lines of four nitrogen hydride species: NH, NH2, o-NH3, and p-NH3. Our chemical models show that the line ratios are sensitive measure of density, temperature, and inferred evolutionary stage. We therefore propose observations of four very cold cores in IRDCs that we have already studied with the SMA; we supplement them with two progressively warmer IRDCs for reference with only a modest increase in time. Our goal is to quantify the early evolutionary stages of IRDC cores before they form stars, and the associated chemical activity in the cloud. We will also use the results to refine our chemical models of the nitrogen hydrides under these conditions. Our team is expert in chemical modeling of dark clouds, IRDCs, millimeter and submillimeter astronomy, and Herschel HIFI data reduction and analysis.

### The Masses of Brown Dwarf Disks and the Disk-Stellar Mass Scaling Relation

Proposal ID: OT2_ipascucc_2

Principal Investigator: Ilaria Pascucci

Time: 46.1 hours priority 2

Category: Brown Dwarfs/Very Low-Mass Stars

Summary:

Theoretical models of planet formation have shown that the masses of protoplanetary disks, which are dominated by gas, strongly affect the resulting planetary architectures. Expanding upon the Herschel KP "Gas in Protoplanetary Systems" (GASPS), we propose here a sensitive Herschel/PACS survey to measure the gas disk masses of a well-characterized sample of very low-mass stars/brown dwarfs (BDs). Our survey has two main goals. First, we will empirically set a limit for the largest planets that can form around BDs and thus elucidate the nature of the few planet candidates discovered around them. Second, we will combine our mass estimates with those acquired within GASPS for intermediate- and solar-masss stars to constrain how the disk mass scales with the mass of the central star. To reach these goals we will use deep PACS exposures to detect the [OI] 63 micron emission line which traces the bulk of the disk mass residing beyond tens of AU from young stars. We will use similar models to those developed within GASPS to convert [OI] line fluxes into gas masses. The sensitivity of Herschel/PACS gives us a unique opportunity to measure disk masses down to the BD regime and to provide the critical observational constraints to planet formation theories.

### Characterizing nearby WISE warm debris disks with Herschel

Proposal ID: OT2_isong_4

Principal Investigator: Inseok Song

Time: 8.5 hours priority 2

Category: Circumstellar/Debris disks

Summary:

Until recently, debris disk identification and study has been accomplished mostly with the 30 year old IRAS all-sky survey (and small number of pointed observations by Spitzer) and it has been limited to larger cold disks. Study of warm debris disks can provide important information concerning terrestrial planet formation and evolution, however, their identification and characterization has been restriected to a very small number of discovered warm debris disks (N<10). The Wide-Field Infrared Explorer (WISE) has surveyed the entire sky at mid-IR wavelenghts, and the WISE survey provides almost 100 times better photometric sensitivity than IRAS and approximately 10 times betterpositional accuracy. Using this improved information and sophisticated target selection criteria, we have identified a complete, well-defined group of 30 nearby (d < 100 pc) Hipparcos main-sequence stars showing the indication of warm debris disks. With nine of these stars being observed as part of an existing Herschel program, we propose to observe the remaining 21 stars to complete a census of warm debris disks in the solar neighborhood. With Herschel PACS measurements at 70 and 160 micron, we can fully constrain dust temperature and dust quantity around this rare group of stars.

### Cataloging Debris Disks within 100pc

Proposal ID: OT2_isong_5

Principal Investigator: Inseok Song

Time: 10 hours priority 2

Category: Circumstellar/Debris disks

Summary:

Although many hundreds of debris disks have been discovered over the past three decades, these stars are widely diversed in terms of ages, distances, reliabilities, levels of dust characterization, etc. Nearest debris disks are most interesting because they are brighter and larger than more distant similar debris disks. By collecting all known debris disks in the literature, we re-analyzed all debris disks (about 1800) in a homogeneous way using the state-of-the-art photosphere fitting method and including the newest available data including WISE. Out of this reanalysis, we selected 123 nearby (d<100[c) bona-fide debris disks where almost a half of them have a dust excess measurement at only one passband. To constrain dust properties for these nearby debris disks, we request to obtain 100 and 160 micron measurements with Herschel/PACS. The result of this proposed study will be a complete inventory of known debris disks within 100pc with fully constrained dust properties. Such an inventory will be an indispensable asset for any future debris disk studies with ALMA, SOFIA, SPICA, etc.

### Beyond the Snow Line: the Oxidation State of Disks and Connections to the Transport and Growth of Icy Bodies

Proposal ID: OT2_jcarr_1

Principal Investigator: John Carr

Time: 43.1 hours priority 2

Category: Circumstellar/Debris disks

Summary:

Herschel offers an unique opportunity to probe the conditions and chemical evolution in the planet formation region of disks, particularly at radii immediately beyond the snow line (~ 1 to 20 AU), the formation zone for asteroids and gas giants in the Solar system. We propose PACS spectroscopy of a small sample of T Tauri star disks in order to investigate the oxidation state of the gas at these radii, a key parameter in gas-phase chemistry and solid-state mineralogy. The proposed data will provide an important observational link between the oxidation conditions implied by known meteoritic properties and T Tauri disks as proxies for the conditions in the early solar nebula. Results from Spitzer already suggest variations in the oxidation state of the warm gas interior to the snow line, based on the observed range in the content of simple organic molecules relative to water. This could result from different efficiencies in planetesimal growth and sequestration of water ice beyond the snow line, differences potentially related to the mass of the disk. The oxidation state outside the snow line is influenced by the radial transport of water vapor and ice, settling and turbulence, and the growth of large icy bodies. The action and efficiency of these processes can leave their imprint on the C/O ratio of gas in the disk atmosphere, with predicted changes in the chemistry. We propose to carry out sensitive PACS spectroscopy of chemical signatures (CO, NH3, HCN and H2O) that can probe the oxidation state at 1-20 AU. The targets are carefully picked to sample a range in disk mass and organic disk signatures inside of the snow line. The combination of Herschel and Spitzer data will allow us to compare the chemistry interior and exterior to the snow line and to better understand the role of physical processes such as the radial migration and growth of icy bodies that affect disk chemical evolution and planet formation.

### The Origin of the Destroyed Planetary Body at G29-38: One of Many Asteroids or a Major Rocky Planet?

Proposal ID: OT2_jfarihi_2

Principal Investigator: Jay Farihi

Time: 9.4 hours priority 1

Category: Circumstellar/Debris disks

Summary:

G29-38 is the prototype and brightest example of a white dwarf orbited by rocky debris from a tidally-destroyed planetary body. Because this warm debris orbits within 1 solar radius, the parent body must have originated in a more distant region. Thus, we suspect a persistent planetesimal belt at G29-38, that contains a substantial number and mass of remnant planetary bodies, as this best accounts for the larger family of disk- and metal -polluted white dwarfs. We propose Herschel PACS observations to detect cold dust from within this remnant population of minor planets. A lack of cool dust favors a scenario in which the observed warm dust resulted from the tidal destruction of a major rocky planet. The proposed observations are the best chance to detect such a cold disk around any metal-enriched white dwarf, and will provide insight into the fate of planetary systems at A- and F-type stars.

### Probing short-term far-infrared variability of protostars and exploring afterglows of X-ray disk heating

Proposal ID: OT2_jforbric_3

Principal Investigator: Jan Forbrich

Time: 7.3 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Recent studies have shown that there is a surprising amount of variability on many timescales in the mid-infrared emission of young stellar objects (YSOs). Especially on short timescales of minutes to hours, mid- and particularly far-infrared variability is currently almost entirely unexplored. While such variability is probing circumstellar disks and envelopes, it is linked to physical processes on the central object. Already the earliest evolutionary stages of YSOs are also strong X-ray emitters, and one important aspect is the heating and possible eventual dispersal of circumstellar disks due to X-ray emission. Even though very important for the understanding of planet formation, this process is poorly understood. The Herschel Space Observatory offers the last possibility for the foreseeable future to explore these processes in more detail and learn about disk heating and explore the occurrence of short-term variability. Here, we propose to do both by repeated observations of the extensively studied nearby Coronet cluster in the CrA star-forming region. Five epochs of near-simultaneous XMM-Newton and Herschel observations, each about 1.5h in duration and spaced by timescales of days to weeks, are meant to explore the short-term variability and link it to the more frequently studied variability on longer timescales. During each epoch, the cluster is mapped 18 times with Herschel. The Coronet has been chosen for having YSOs that can be detected at high S/N in short periods of time while not being too crowded for the angular resolution of both observatories. By exploring far-infrared variability on timescales of several minutes to days and weeks as well as disk heating by protostellar X-ray emission, these short observations will have a unique legacy value.

### Mapping Sagittarius B2 a starburst in the Milky Way's Galactic Center

Proposal ID: OT2_jgoicoec_5

Principal Investigator: Javier R. Goicoechea

Time: 10.8 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

We propose to use the SPIRE-FTS to map a 8.5'x8.5' (~20pc x20pc) region around Sgr B2, the only source that allows studying a burst of star formation in the center of a galaxy (GC) with high spatial resolution even using a single dish telescope (25'' = 1 pc).

Bright high-mass star forming regions do exist in the disk of the galaxy, but the specific location of Sgr B2 in the GC (where the ambient physical conditions are markedly different compared to the disk) make it the best source to compare with unresolved extragalactic nuclei (M82, the prototype starburst galaxy is ~400 times more distant and thus 25''=400 pc).

Our SPIRE-FTS pointed observations around Sgr B2(M) core and surroundings show strong dust continuum emission as well as emission lines from 12CO and 13CO rotational ladders; [NII] and [CI] fine structure lines; emission/absorption of excited H2O and NH3, and line-of-sight absorption of a variety of light hydrides (HF, CH+, CH2, OH+, H2O+, H3O+, NH and NH2) that are difficult, if not impossible, to detect from the ground. Even far from Sgr B2 star forming cores, the expected continuum and line intensities will enable us to map tens of lines over large areas in very reasonable times.

Understanding the large scale physics and chemistry of this starburst template in the GC is of great interest as recent Herschel observations are revealing similarly rich spectra in fainter galaxies where, of course, different components overlap in the beam. The proposed spectral maps and SEDs will form a large database that will be a legacy for higher angular resolution studies of extragalactic nuclei.

### SPIRE-FTS Observations of a Diverse Sample of Protostars and their Surroundings

Proposal ID: OT2_jgreen02_6

Principal Investigator: Joel Green

Time: 30.9 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

We propose to observe a diverse sample of protostars with Herschel-SPIRE, selected from the DIGIT/WISH programs, to answer the key question: To what extent can we separate the system properties of a protostar (e.g. envelope/disk) from the extended properties (e.g. outflows, fast shocks)? Quantifying energetic feedback from a protostar into its surrounding environment provides a key for understanding the star formation process. Because of its simple chemistry and high abundance, CO is an ideal tracer of such feedback. We have the unique opportunity to expand a well-studied dataset of low-mass protostars with a huge range of existing observations: PACS and IRS spectroscopy, ancillary IR/optical/UV/X-ray and millimeter data, selected from the WISH/DIGIT that span a variety of bolometric luminosities and temperatures. Observations of mid-J CO lines are the missing link that we need to separate the effects of outflow from envelope emission.

### Completing the Herschel Survey of Cygnus-X

Proposal ID: OT2_jhora_2

Principal Investigator: Joseph Hora

Time: 15.5 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Massive stars are rare and distant. Their short-lived protostellar phases are therefore difficult to study, and the processes that produce them are not well understood. The Cygnus-X complex is one of the richest known regions of star formation in the Galaxy at a distance of ~1.3 kpc, which allows it to be studied at smaller scales and less confusion than other similarly active regions that are more distant. We have conducted a Spitzer Legacy survey of the Cygnus-X region and used the data to map the distribution of Class I and II YSOs in the complex, and have begun to study the interaction between the massive young stars and clusters of low-mass YSOs. We propose to use PACS and SPIRE to complete an unbiased survey in the Cygnus-X region to detect the intermediate to high-mass young stellar objects, pre-stellar cores, and infrared dark clouds (IRDCs) and their embedded objects. The Herschel observations, in conjunction with the existing Spitzer, near-IR, and other ancillary datasets will allow us to assemble a comprehensive picture of star formation in this high mass, extremely active complex. With the Herschel data we will 1) complete the sample of massive protostars and YSOs in Cygnus-X and construct SEDs of the objects from 1 to 1200 microns, 2) use the derived luminosities and envelope masses from the sample to construct evolutionary diagrams and test high-mass star formation models, 3) analyze the population of Infrared Dark Clouds in Cygnus-X, and 4) explore the role of massive stars in triggering star formation in surrounding clouds. The data will provide a useful resource for the study of star formation for years to come.

### Maddalena's Cloud: A unique Laboratory for Early Evolutionary Stages of massive GMCs?

Proposal ID: OT2_jkauff01_3

Principal Investigator: Jens Kauffmann

Time: 12.9 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

We propose to establish the evolutionary state of Maddalena's Cloud. This region is regularly discussed as a prototype for a giant molecular cloud (GMC) in an early phase of its life. This suggestion is based on the fact that this region of about 3x10^5 M_sun is entirely devoid of embedded massive stars. Thus, this region potentially presents an ideal site to study the initial conditions for the evolution towards clouds like Orion A. This is not entirely clear, though: it has also been argued that this cloud might be at the end of its life, and is now dispersing after being "stirred up" by previous star formation. We therefore propose to execute two complementary experiments to establish the cloud's evolutionary status. Both will use wide-field parallel mode SPIRE/PACS dust emission maps. First, we will obtain the first reliable estimates for the mass of the cloud and its clumps to revise the --- presently very uncertain --- virial analysis on which suggestions for cloud dispersal are based. Second, we will search for deeply embedded young stellar objects (YSOs): if these very young (class 0-I) YSOs exist throughout the cloud, it would be hard to argue that this is a cloud in which star formation is ending. Depending on these experiments, our data will then be used to constrain the physical conditions in the early life of massive GMCs. Certainly, the properties of this cloud are unique: we only expect to find about 6 such massive clouds without O stars within 2.2kpc from sun. This is the only cloud of this sort we presently know, and so our observations will have a significant legacy value for studies of star formation.

### An accurate mass measurement for prestellar cores

Proposal ID: OT2_jkirk_3

Principal Investigator: Jason Kirk

Time: 11 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Prestellar cores are crucial to our understanding of star formation. It is at this evolutionary stage that the stellar mass is set. If we are to understand the origin of the stellar IMF, we must therefore study the masses of the prestellar cores from which the stars are formed. There is currently a large uncertainty in the measured prestellar core mass that we obtain from far-IR and submillimetre observations. This uncertainty is caused by our inability to simultaneously determine the column density, temperature and dust emissivity index from photometric observations. Physical processes such as grain growth, or ice-mantle formation, which are affected by changes in density and temperature, will change the dust emissivity index. By simply taking a canonical value for the emissivity index, we cannot determine the correct mass for prestellar cores.

The SPIRE FTS allows us to break this degeneracy for the first time, and simultaneously measure the column density, temperature and dust emissivity index, and therefore determine accurate masses. We propose to map 16 prestellar cores with the SPIRE FTS, and hence generate accurate maps of their column density. We will map each core using the full FTS field of view. We will be able to determine the absolute value of the dust emissivity index, and also see whether it varies across each of the cores. We have selected cores in different environments in order to study the core-to-core, and cloud-to-cloud variations in the dust properties. We will be able use this information about the relation between the three measured parameters, to more accurately determine masses for a much larger sample of cores for which only photometric data are available

### Searching for the First XDR around a Low Mass Star Forming Region

Proposal ID: OT2_jlee01_2

Principal Investigator: Jeong-Eun Lee

Time: 9.3 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

We propose to observe the compact but well-studied protostellar core L1251B with all Herschel instruments. L1251B harbors potentially the first XDR ever isolated (there are two strong candidates) and is the only low mass source that we have an existence of the detailed maps of ice evaporation. Therefore, we propose to observe L1251B in [N II] 205.4 micron and the ground state p-H2O lines with HIFI to study the effects by high energy photons produced through the accretion process in early evolutionary stages. This will be supplemented with PACS full SED and SPIRE FTS modes. This combined data set will confirm the potential presence of the first low mass XDR. They also will allow for the only source where Herschel can connect water vapor and water ice emission to Spitzer maps of water ice absorption on equivalent spatial scales.

### Confirmation and characterisation of two debris disks around low-mass stars.

Time: 6.5 hours priority 1

Category: Circumstellar/Debris disks

Summary:

Debris disks surrounding main sequence stars are analoguous to the Kuiper Belt around the Sun and are signposts for exoplanetary systems according to planet formation theory. Low-mass stars (M-stars) are challenging targets for both exoplanet searches and debris disk searches. However, they are vital for understanding planet formation in complement of higher mass stars. With Herschel, we propose to confirm and characterise two M-star candidate disks while only two others are presently known among low-mass stars.

The two M-stars, GJ842.2 and HD95650, have candidate disks from SCUBA and Spitzer observations. We propose to make PACS images that are deep enough to detect their photospheres in order to verify unambiguously position coincidence between stars and disks. This approach could not be accomplished by neither SCUBA nor Spitzer. Additionally, it is reasonable to speculate that these disks will be large enough to be resolved by PACS providing definite proof of their nature. Finally, we request SPIRE in complement to PACS to fully sample the SED of the dust emission in order to determine their fractional dust lumninosities and dust properties.

One of the key question in debris disk studies today is to understand the physics responsible for the trend apparent in their detection fractions indicating fewer debris disks around lower-mass stars. Several physical clues have been suggested; for instance, observed and theorised lack of massive gaseous planets around M-stars could reduce disk stirring and so dust production. It is vital to expand the number of known disks around M-stars to tackle this key question. By resolving two new disks and modelling their images, we shall infer the scale of the planetary systems around M-stars and be able to measure the size of the inner hole hosting planets. Asymmetries in their images would be indicative of resonances with planets. The scarcity of known disks around M-stars makes these observations crucial.

### The Galactic center as the laboratory to understand nuclear activity in galaxies (GC_JMP)

Proposal ID: OT2_jmartinp_4

Time: 55.3 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

We propose to use the The Galactic center (GC) a local extragalactic laboratory to understand the chemistry and the heating mechanisms in nearby galactic nuclei. The central 30 pc region around the black hole, Sgr A*, contains all the different type of activity found in extragalactic nuclei, namely, massive stellar clusters creating large photodissociation regions (PDR), shocks, molecular clouds irradiated by strong X-rays (XDRs), and the site of Cosmic Rays (CRs) acceleration as shown by HESS. We plan to map this region with SPIRE in the high spectral resolution mode and with HIFI in selected molecular ions H$_3$O$^+$, OH$^+$, and H$_2$O$^+$ claimed to trace XDRs and/or CRs. This unique data set will provide the possibility to understand the origin of the large column densities of this hydrides found in galactic nuclei with different type of activity and the role of the PDR-XDR-CR chemistries in their formation. The SPIRE data cubes will have a huge legacy value providing the full FIR inventory of the atomic and molecular gas across the central 50 pc of the Galaxy. We stress that only the combination of the high spectral resolution of HIFI and the spatial distribution provided the proposed mapping will have the possibility to distinguish which of the different components of the molecular gas along the line of sight correspond to the ones associated with XDRs PDRs and eventually CRs acceleration sites.

### Cooling and chemistry in embedded massive protostars in the Magellanic Clouds

Proposal ID: OT2_joliveir_2

Principal Investigator: Joana Oliveira

Time: 38.8 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

Stars form from contracting molecular cores, but this process relies heavily on the ability of the core to cool. This depends on chemical composition and could therefore lead to different outcomes at low metallicity. However, most of what we know about star formation is derived from studies of Galactic YSOs. Herschel provides the unmissable opportunity to extend such analysis to the low-metallicity environments of the Large and Small Magellanic Clouds (LMC and SMC), by observing the main cooling lines: fine-structure lines of oxygen and carbon, and rotational transitions of abundant molecules.

Our Spitzer Legacy Programs (SAGE; SAGE-SMC) and Herschel Key Program (HERITAGE) identified 1000s of young stellar objects (YSOs), in both Clouds. Follow-up spectroscopy (Spitzer-IRS and ESO/VLT) provided unique insight into the abundances of ices in Magellanic YSOs, revealing differences in the composition of circumstellar material at lower metallicity. Since the gas and ice phase chemistry is inextricably linked, this opens the possibility of significant variations to gas-phase abundances. Such differences could imply changes to cooling and heating rates, and consequently different star formation timescales and efficiencies.

To investigate the role of metallicity we will observe a sample of embedded massive Magellanic YSOs. We will use PACS and SPIRE FTS spectrographs to measure the strengths of key gas-phase cooling species ([OI], [OIII], [CII], H2O, CO, OH), in order to estimate temperature, density, ionization state and abundances. These observations will enable us to characterise the gas and constrain the cooling budget of the YSO envelopes. Together with our ice column density measurements, the Herschel observations are crucial to investigate how grain-surface reactions change the chemical make-up of the gas.

By comparing the SMC and LMC, and Galactic YSO samples we will assess how the chemistry, and consequently the ability of the YSO envelopes to cool, differ at sub-solar metallicity.

### Search for Edgeworth-Kuiper Belt Analogs in the Alpha Perseus Cluster

Proposal ID: OT2_jrhee_1

Principal Investigator: Joseph Rhee

Time: 17.7 hours priority 2

Category: Circumstellar/Debris disks

Summary:

Advances in understanding planet formation and evolution can be gained from studying how frequently debris disks form and how they interact in different environments over time. While field stars near Earth enable small quantities of dust to be detected, the nearest rich open clusters -- with their well constrained ages -- enable one to infer how debris disk characteristics evolve with time as a function of spectral type and birth environment. Located ~172 pc from Earth, the ~60 Myr old Alpha Perseus cluster is the only substantial and nearby young open cluster or moving group that was not targeted by the Spitzer Space Telescope, yet its richness provides an excellent laboratory to address fundamental, debris disk-related, questions. Recently we identified a dozen or so Alpha Per members to have mid-IR excess based on the published WISE catalog. Previous studies of debris disks have demonstrated that significantly more stars have dominant excess emission at 60 micron than at mid-IR wavelengths, implying the potential presence of a large population of stars with cold debris disks -- analogous to the Sun's Edgeworth-Kuiper Belt -- in Alpha Per. We propose to observe 97 early-type members of Alpha Per with PACS at 70 and 160 microns; these will provide far-IR photometry for a complete sample of known Alpha Per A- and F-type stars.

### Probing the gas in the outer Galaxy: Molecular or Atomic?

Proposal ID: OT2_jstutzki_3

Principal Investigator: Juergen Stutzki

Time: 9.2 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

Despite of all theoretical speculations and various observational constraints, the nature of the dark matter in the outer Galaxy is still unknown. Herschel/HIFI offers the unique opportunity to detect or set a significant upper limit to a potential component of baryonic matter in the form of cold gas, which is molecular in hydrogen, but does not form CO. Such gas can be potentially be traced through [CII] 150 um and HF J=1-0 absorption against continuum background sources. We propose a set of 7 the brightest outer Galaxy dust continuum sources, for which we will determine the positions of peak emission by PACS mapping. Deep integrations in [CII] and HF towards the 4 brightest peaks in these sources will potentially detect a cold gas component and will, in any case, give significant upper limits to its column density.

### Far Infrared Extinction (FIREX)-Mapping the Initial Conditions of Massive Star Formation

Proposal ID: OT2_jtan_1

Principal Investigator: Jonathan Tan

Time: 5.9 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

The initial conditions of massive star and star cluster formation are likely buried in the densest, coldest and most obscured regions of giant molecular clouds (GMCs). We propose to use this obscuration to our advantage by carrying out sensitive, high angular resolution 70, 100, and 160 micron PACS imaging of 10 Mid-Infrared Dark Clouds (IRDCs). Building on our experience of Mid-IR extinction (MIREX) mapping, we will apply a new analysis method of Far-Infrared extinction (FIREX) mapping to derive estimates of the mass surface densities and temperatures of massive starless cores and clumps. Compared to the 8 micron-derived MIREX maps, 70 micron-derived FIREX maps will be able to probe to at least 4 times higher values of mass surface density, into a regime >1 g/cm^2, which some theories predict is a necessary condition for massive stars to form. The high angular resolution 100 micron images are crucial for disentangling temperature variations in the IRDCs, which can mimic 70 micron absorption. This analysis will be aided by comparing with the lower resolution 160 micron images and Hi-GAL SPIRE data. It is possible that absorption at even 100 microns will be seen, picking out the very densest, coldest regions.

We note that while 70 micron (but not the crucial 100 micron) data exist for these IRDCs from the Hi-GAL survey, our proposed observations will have much improved angular resolution and flux sensitivity because of the use of a slower scanning speed. This is important to probe the highest mass surface density cores and clumps, which we know contain sub-structure down to scales at least as small as the resolution of the proposed images, ~5 arcseconds.

This project requires the stable FIR photometry that is only possible with Herschel PACS. At the same time unique science questions, resulting from probing the most extreme mass surface density regions yet studied by extinction mapping, can be carried out with a modest amount of observing time of just under 6 hours.

### Characterizing the Energetics of the Youngest Protostars: PACS Spectroscopy of Herschel-Identified Extreme Class 0 objects in Orion

Proposal ID: OT2_jtobin_2

Principal Investigator: John Tobin

Time: 10.6 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

We propose to observe a sample of nine very red protostars serendipitously identified in PACS observations for the Herschel Orion Protostar Survey (HOPS). In contrast to the known Orion protostars targeted in HOPS, the new sources are undetected or very faint in Spitzer 24 micron imaging of Orion. They are redder than the known Orion Class 0 protostars, and appear similar to the most extreme Class 0 objects known. These objects are likely to be in a very early and short lived stage of protostellar evolution.

With this sample, we aim to determine if the youngest protostars begin their lives in a violent energetic phase or in a more quiescent manner, slowly building their accretion and outflow power. To do this, we propose PACS Range Spectroscopy between 70 and 200 microns, observing the CO and H2O lines, and line spectroscopy centered on the 63 micron [OI] line. These far-IR cooling lines are powerful diagnostics of shock heating by outflows and radiant UV heating from accretion luminosity. Through a comparison with existing HOPS observations, these observations will be a unique window on the early evolution of outflows and accretion in protostars.

### Differential Heating of Magnetically Aligned Dust Grains

Proposal ID: OT2_jvaillan_1

Principal Investigator: John Vaillancourt

Time: 2.1 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

The observations proposed here are designed to search for the effect of differential heating on asymmetric dust-grains aligned with respect to an interstellar magnetic-field and heated by a localized radiation source. The grains are known to be asymmetric and aligned from observations of background starlight polarization. Modern theories on grain alignment suggest that photons from stars embedded in the foreground cloud are a key ingredient of the physical mechanism responsible for alignment. This theory predicts a relation between the grain-alignment efficiency and the angle between the magnetic field and the direction to the aligning radiation-source. This effect has been tentatively observed in a source with a very simple geometry: the aligning photons are primarily from a single localized source (i.e., a singe star) and the local magnetic-field direction is known to be fairly uniform. Such a region also has consequences for the distribution of grain heating. For example, asymmetric grains whose largest cross-sections are normal to the incident stellar radiation will reach warmer equilibrium temperatures compared to grains whose largest cross-section is parallel to that direction. This should be observed as an azimuthal dependence of the dust color-temperature. As we show in this proposal, such a dependence is hinted at in work using IRAS data at 60 and 100 micron. If this effect is real then a stronger signal is expected using longer wavelength data. Here we propose to search for this signal using Herschel/PACS photometry at 100 and 160 micron.

### V838 Mon: aftermath of a stellar merger

Proposal ID: OT2_kexter_2

Principal Investigator: Katrina Exter

Time: 1.6 hours priority 1

Category: Galactic Other

Summary:

V838 Mon is one of the most enigmatic objects observed in stellar astrophysics in recent decades. It came to attention when it underwent a powerful eruptive outburst in Jan. 2002, increasing in luminosity by a factor of 100 over a period of 3 months. Immediately following this event a spectacular light echo was formed from the outburst light reflecting off the surrounding dust. The theories that best explain the outburst are a giant star engulfing a planetary system or a merger between a very low mass star and a very young, maybe pre-main sequence low-intermediate mass star. We obtained PACS and SPIRE (and will obtain HIFI) data of the star and the surrounding dust from a GT1 proposal. From the PACS and SPIRE maps we can see that the extended emission varies with wavelegth, and hence in dust condtions. In addition, by comparing to previous Spitzer images, we can see that the morphology of the extended emission (ISM dust) and the flux of the unresolved source (new dust forming around the star) have changed between 2004, 2007 and 2011. Hence, in this proposal we are asking for 2 additional epochs of imaging, to follow the evolution of all of this dust.

### Search for the H2F+ ion

Proposal ID: OT2_kkawaguc_1

Principal Investigator: Kentarou Kawaguchi

Time: 4.4 hours priority 1

Category: Interstellar Medium/HII regions

Summary:

By using new laboratory transition frequencies of the H$_2$F$^+$ ion, we propose a search for the ion in interstellar space. The detection will contribute to understanding the fluorine chemistry through determined abundances of fluorine bearing molecules.

The precursor of H2F+, the HF molecule detected in diffuse molecular cloud towards W49N has a fairly large abundance of $(5.5-6.9) \times 10^{13}$cm$^{-2}$ Since the dipole moment of H$_2$F$^+$ 2.79 D is large compared with 1.89 D of H$_2$Cl$^+$, the H$_2$F$^+$ ion may be detectable in such diffuse molecular clouds where H$_3^+$ is abundant.

By considering various things, we propose searches for H$_2$F$^+$ toward three types of sources, (1) G10.6-0.4(W31C), where HF has been detected, (2) NGC 6334I, where H$_2$Cl$^+$ has been detected, (3) galactic central region sources : GC IRS 21 and 2Mass J1747, where H$_3^+$ is known to be abundant. For NGC 6334I and galactic sources, HF observations are also proposed, because of no reports for HF.

### The distribution of water vapor in protoplanetary disks and their winds

Proposal ID: OT2_kponto01_2

Principal Investigator: Klaus Pontoppidan

Time: 42 hours priority 2

Category: Circumstellar/Debris disks

Summary:

One of the key mission objectives of Herschel is to understand the role of water vapor in various environments, including in protoplanetary disks. Water has an immediate relevance to the formation of planets and to our own origin. We propose to obtain deep PACS/SPIRE line spectra of water, OH and CO in protoplanetary disks selected to have strong rotational water vapor emission at mid-infrared (10-36 micron) wavelengths (the newly discovered mid-infrared molecular forest). The mid-infrared lines trace warm to hot gas formed within a few AU from the central star. The proposed observations will relate the oxygen chemistry and transport of water in the inner few AU with that of the cooler outer disk - 1-100 AU - as traced by the PACS water lines. The Spitzer observations suggest that water vapor may be strongly depleted in the disk surface beyond 1 AU although gas and dust temperatures are high enough to maintain abundant water in the surface out to at least 10 AU. It is not understood whether this is due to chemical effects, radiative transfer effects or whether the water vapor can diffuse downwards to colder layers where is can freeze out and settle to the midplane. Measuring the radial abundance structure of the water emission by combining Herschel and Spitzer spectroscopy of water vapor is a critical step to distinguish between these scenarios and to constrain detailed disk models. Based on model fits to the mid-infrared lines, we predict very strong differences in the 50-200 micron water lines, depending on the distribution of water in the outer disk surface. We requested time to observe 8 disks in OT-1, but were awarded time for 4. This is a proposal for time to observe the remaining 4 in order to gain statistical confidence across a range of disk accretion rates and to probe the influence of disk winds on the properties of the distribution of water vapor.

### The Final Four: Completing Herschel's Imaging Legacy for Key Debris Disk Systems

Proposal ID: OT2_kstape01_1

Principal Investigator: Karl Stapelfeldt

Time: 3.7 hours priority 1

Category: Circumstellar/Debris disks

Summary:

Debris disks are the signposts of planetary systems: collisions among asteroidal and cometary parent bodies maintain the observed dust population against losses to radiation pressure and P-R drag. While hundreds of debris disks are known from far-IR excecss emission around main sequence stars, the best- understood systems are the ~20 that are spatially resolved. Disk images establish the size scale of an exoplanetary system. They can reveal central holes, rings, gaps, warps, and asymmetries in the dust distribution which indicate the presence of planetary perturbers. Disk images at different wavelengths are sensitive to dust grains of different sizes, and thus provide a way to trace dust transport and segregation processes.

In spring 2011 we discovered large new debris disk in HST coronagraphic images. The new system is an eccentric ring with a sharp inner edge and cleared central zone, and thus is remarkably similar to the classic Fomalhaut debris ring. Spitzer only detected the system at a single wavelength. We propose PACS and SPIRE imaging photometry to fully establish the spatial and spectral properties of this new debris system, and of three other HST-detected debris disks that lack Herschel measurements. Simultaneous modeling of the far-IR images, SEDs, and HST images of these disk will provide important constraints on the physical properties and dynamical state of their constituent dust. Our small program will complete Herschel's legacy dataset for the key subsample of bright disks that are detected in scacttered light,

### Characterization of Outer Exoplanetary Systems With Herschel Imaging

Proposal ID: OT2_ksu_3

Principal Investigator: Kate Su

Time: 13.7 hours priority 2

Category: Circumstellar/Debris disks

Summary:

Our knowledge of planetary systems outside of ours is confined almost entirely to cases where the planets are close to the star. A critical stage in the development of the Solar System was the stabilization of the orbits of Jupiter and Saturn far from the Sun. What are the characteristics of other planetary systems at large radii? Planetary debris disks provide our best tool to answer this question. However, our interpretation of these systems is currently crippled by the lack, in most cases, of more information beyond a few photometric points on a spectral energy distribution. Such data can be fitted by a broad variety of quite different disk models. Resolved Herschel images of disks can provide much better constraints on models and can lead to sufficient understanding of the general behavior to help interpret even those systems where resolved images are not possible.

We have identified 17 bright disks that show marginally resolved structures in Spitzer data, suggesting a radial size of cold planetesimal belt 3 to 10 times larger than our own Kuiper Belt. Since the disk mass is proportional to the disk diameter and covering factor of the dust, these systems are likely to be associated with the most massive planetary systems, making them the possible sites where the richest, most massive and extended families of planets will form. We propose to image these disks that can be resolved well at PACS 70 micron but not in any existing Herschel programs. We will use the resolved images as well as the photometric data obtained with SPIRE to probe: (1) the properties of cold planetesimal belts as signposts of ice giants at large orbits, and (2) the diversity of outermost planetesimal zones around other stars and the underlying causes.

### Tracing the dark gas in the Perseus Molecular Cloud Complex with Herschel

Proposal ID: OT2_kwillacy_1

Principal Investigator: Karen Willacy

Time: 31.6 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

Understanding the composition and physical conditions of gas in the Galaxy is crucial for understanding its structure and evolution. A great deal of information is available concerning the distribution of atomic and molecular gas but traditional tracers such as CO and HI are not able to trace regions where the gas is dense enough for H2 to exist, but where any CO and other molecules are photodissociated. These regions have been called dark gas' (Grenier et al. 2005) and have been shown to make up ~ 30% of the molecular gas in our Galaxy. If we rely on CO, therefore, we will miss a large, important component of the molecular gas budget of the Galaxy. Our goal is to use the CII emission to trace and characterize the dark gas layer in the Perseus molecular cloud complex. Here we propose an observing program to make sparse maps of the CII emission along several cuts through Perseus allowing us to trace the transition from C+ to CI. We also propose to make maps of the CI emission over the CI to CO transition zone. We will combine the Herschel observations with already existing CO and extinction maps to determine the physical conditions in the dark gas and hence to better understand the transition from diffuse to molecular gas at the edges of molecular clouds.

### Tracing Galactic Metallicity with Herschel

Proposal ID: OT2_landerso_1

Principal Investigator: Loren Anderson

Time: 17.2 hours priority 2

Category: Galactic Structure

Summary:

Galactic abundances trace the processing of primordial elements by stars from the birth of the Milky Way to the present day. HII regions, because of their short lifetimes, are ideal targets for abundance determinations because they sample the current state of the interstellar medium. We propose to observe the [OIII], [NIII], and [NII] lines of 31 well-studied Galactic HII regions with the PACS spectrometer to derive the oxygen and nitrogen abundances. We hope to address two long-standing problems in Galactic abundance measurements: 1) abundances traced in the far-infrared show discrepancies with those in the optical, and 2) HII region electron temperatures derived from radio observations, which can be used as a proxy for metallicity, are not well calibrated with abundance measurements.

### Characterizing a Complete Resolved Star Formation Region: NGC 602 in the SMC - Beautifully Alone

Proposal ID: OT2_lcarlson_1

Principal Investigator: Lynn Carlson

Time: 9 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

We propose to map the isolated star forming region NGC 602 to characterize the temperature and density structure of the entire system. NGC 602 lies in the periphery of the Small Magellanic Cloud and is the ideal target for a complete study of a star forming region. It is distat enough (at 60 kpc) that we can map the entire region in a short time but near enough that the stellar population and the structure of the interstellar medium (ISM) are resolved. Its isolation, in the outskirts of the galaxy, means that there is virtually no line-of-site confusion, and the interstellar radiation field arises entirely from cluster stars. We have already fully characterized the stellar and protostellar content using data from the Hubble and Spitzer Space Telescopes. Now we will explore how the massive main sequence stars are driving current star formation via their influence on the surrounding ISM. We will map the photodissociation region (PDR) in the dominant [OI] 63 micron and [CII] 158 micron fine-structure cooling lines with the PACS spectrometer and in high-resolution 70 micron PACS photometry. They will allow us to probe the temperature and density structure of the PDR. We will combine these new data with our Spitzer SAGE-SMC (IRAC 3.6-8.0 micron, MIPS 24 micron) and Herschel HERITAGE (PACS 100 and 160 micron, SPIRE 250, 350, and 500 micron) broad-band imaging as well as HST optical data to integrate a picture of massive stars, star formation, and their connection with the interstellar medium on the scale of a well-defined OB association.

### Heating and cooling mechanisms in massive star forming regions

Proposal ID: OT2_lchavarr_1

Principal Investigator: Luis Chavarria Garrido

Time: 20.1 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

We propose HERSCHEL observations of molecular and atomic transitions to study the heating and cooling balance in the surroundings of young massive stars. The high spectral and spatial resolution of the HERSCHEL space telescope gives an unique opportunity to observe the most relevant cooling and heating transition lines at wavelengths which are non observable from ground-based telescopes. The objective of our proposal is to understand the role of cooling during the early stages of massive star formation. Is cooling dissipating enough energy and allowing high accretion rates in young massive stars? Where is the cooling mainly taking place in massive protostars? Addressing these questions will help us to disentangle between different theories of high-mass star formation.

### A Sensitive Search for OH and H2O in the Cold Outer Layers of Planet-forming Disk

Proposal ID: OT2_lcleeves_1

Principal Investigator: L. Ilsedore Cleeves

Time: 11.8 hours priority 1

Category: Circumstellar/Debris disks

Summary:

One of the biggest results that have come from Herschel HIFI is the detection of cold water vapor where it would otherwise be frozen onto grains (Hogerheijde et al. 2011, Bergin et al. 2010). Surprisingly, one unexpected inference of these observations is the requirement that the photo-desorption of water be reduced by nearly an order of magnitude to reproduce the emission line observations. The interpretation of these results was the existence of a population of dry' (reduced water-ice-coated) grains on the surface of the disk. Emission line data, however, is intrinsically model dependent with many uncertainties, even in the collisional rates. We propose here a test of the models used to reproduce the Herschel observed water emission using an absorption line study of the main photo-desorption products of water, namely gas-phase H2O and OH. This type of study is intrinsically more sensitive as it is a direct measure of the column, without the need to assume anything about the excitation conditions. Both H2O and OH are expected to be predominantly in the ground state, and therefore such a study is the only direct test of the bulk-water-vapor reservoir. This program is designed to optimize the opportunity to find water and OH in a T Tauri disk both with the ideal inclination and continuum. These results will robustly test theories of water formation in disk systems, namely the presence of a cold, UV-photodesorbed layer of water vapor sitting on the disk surface as inferred by Herschel emission measurements of T Tauris.

### Probing the Dominant Ion on the Surface of Planet-Forming Disks with Herschel/HIFI

Proposal ID: OT2_lcleeves_2

Principal Investigator: L. Ilsedore Cleeves

Time: 14.4 hours priority 2

Category: Circumstellar/Debris disks

Summary:

C+ is expected to be the dominant ion tracing the ultraviolet (UV) radiation exposed layers of young T Tauri disks. However, observational evidence of its existence has thus far eluded us. Current Herschel Key Programs using PACS include the detection of C+ as a key program facet; however, these studies have faced substantial difficulties (galactic background, strong continuum/narrow line width) in their ability to detect this intrinsically weak line. We have designed an optimized Herschel HIFI program to finally detect this line in a sample of disk systems which span a range of dust settling, and thus a range of gas mass exposed to UV radiation. This will provide a Herschel legacy product to test models of UV radiation transport and the resulting chemistry. This lies at the heart of the detailed models of disk chemistry. Therefore, this information will be crucial as we enter the era of ALMA, where resolved observations will require sophisticated modeling to interpret.

### Disentangling energetic feedback in low-mass protostars with CO 16-15

Proposal ID: OT2_lkrist01_2

Principal Investigator: Lars Kristensen

Time: 14.1 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

During the earliest embedded stages of star formation the young star interacts with its surroundings through high velocity shocks and UV radiation, providing feedback on the medium from which the star is forming. At the same time, in-falling gas is heated to several 100 K by the accretion luminosity. How much energy is lost from the system through each of these processes? Is there an evolutionary trend in terms of the relative contributions from shocks and UV radiation? To address these questions and to observationally differentiate the different heating mechanisms, velocity-resolved observations are required.

Herschel-PACS has revealed that highly excited CO emission (up to J=44-43; Eup ~ 5400 K) is present towards most low-mass protostars, revealing a warm/hot component not detected previously with ISO. The PACS observations reveal directly that CO is one of the best tracers of energetic processes in protostars. To quantify emission, a model was constructed incorporating the shock- and UV-heating mechanisms. While the model is successful in reproducing observations from three sources, it also makes very specific predictions regarding the line-shape of velocity-resolved high-J CO emission. The model furthermore predicts an evolutionary sequence where CO emission in younger sources is dominated by shock heating, as opposed to UV-heating being dominant at later evolutionary stages.

To test the model and its validity for more than three sources, we propose to observe the highest excited CO line possible with HIFI, the CO 16-15 line. Velocity-resolved data will immediately allow us to quantify how much emission is caused by the different heating mechanisms. Furthermore, such data will allow us to measure the different heating contributions for this line directly, thus benchmarking our model and its underlying assumptions.

### Disentangling the water chemistry of the spectacular outflow BHR71

Proposal ID: OT2_lkrist01_3

Principal Investigator: Lars Kristensen

Time: 19.5 hours priority 1

Category: Star Formation/Young Stellar Objects

Summary:

At the earliest stages of low-mass star formation, observations show that mass accretion is associated with mass ejection in the form of collimated jets and bipolar outflows. The ejection activity can be traced as shocked regions, where shock waves originating from the central young stellar object (YSO) impact, and process the ambient interstellar medium (ISM) from which the star forms. This interaction generates molecular emission that is typical of the physical (temperature, density) and chemical (abundances) structure of the gas. Studying this molecular emission is the best way to understand the physical and chemical processes operating in shock regions.

We propose to follow the water chemistry through one of the most spectacular and best-studied outflows in the Southern sky, BHR71. Because the water abundance is very susceptible to energetic input (both through direct formation in the gas-phase and through release from ice-coated dust grains), it is one of the best shock tracers. To trace the water chemistry accurately, velocity-resolved observations are required to disentangle different excitation regimes.

Early Herschel results show that water excitation conditions resemble those of rotationally excited H2, i.e., high densities and temperatures of 300-1000 K. Currently, it is not possible to velocity-resolve rotational H2 lines. Herschel-HIFI has revealed that the water line profiles observed to date are very complex, and they look nothing like the spectra of other molecular traces. Water is therefore a unique tracer of the bulk of the shocked gas where the temperature is 300-1000 K.

Given the importance of BHR71 as the most chemically rich outflow in the southern sky, that makes it a key benchmark for outflow and shock modelling with ALMA, we propose to map this outflow in a few key H2O lines with HIFI. The maps will provide legacy-value information on water and shock excitation as a function of position and velocity throughout the outflow.

### The Evolution of Massive Star Forming Regions: PACS Spectral Scans of Massive Protostars in the LMC

Proposal ID: OT2_llooney_3

Principal Investigator: Leslie Looney

Time: 49 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

Understanding massive star formation is a critical piece of the star formation puzzle, yet we still do not have an unambiguous evolutionary sequence for massive stars and their environments. Herschel is the key to establishing such a critical evolutionary sequence. Probing the evolutionary sequence of massive star forming regions requires an unbiased sample of massive protostars with comparable spatial resolution. We have the largest, most complete spectroscopic sample of massive protostars: 277 sources greater than 8 solar masses observed with Spitzer in the Large Magellanic Cloud (LMC). In this proposal, we request PACS full spectral scans of 25 massive protostars (the smallest statistically varied subsample) from our survey. These 25 sources are an excellent massive protostellar laboratory as they likely span evolutionary states (from deeply embedded to revealed), are all at a common distance, are located uniformly in the LMC, have protostellar properties as derived from SED fits to the emission (giving masses, envelope properties, etc.), and exhibit other emission mechanisms (molecular gas, free-free emission, masers, etc.). We selected the 25 of our brightest sources (>20 solar masses) that dominate the emission of its clump.

In the process of establishing an evolutionary sequence for massive star formation and its environment, Herschel will provide valuable information of the protostellar regions (detections of heated envelopes, location of shocks, PDRs, etc.), and with our sample, we can observe how the spectra change throughout different evolutionary stages. Utilizing a similar approach to our Spitzer data, we will quantify spectral features through SED and radiative line transfer fitting, as well as the powerful technique of principle component analysis, which can only be accurately achieved with full spectral scans that will reap ancillary benefit for years to come.

### The physical and chemical state of high-mass pre- and proto-stellar coresidentified by the Hi-GAL survey

Proposal ID: OT2_lolmi_3

Principal Investigator: Luca Olmi

Time: 28.5 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

We propose to investigate the physical, chemical and dynamical properties of a sample of newly found high-mass pre- and proto-stellar cores identified by the Herschel infrared GALactic Plane Survey'' (Hi-GAL; Molinari et al. 2010). We will perform observations of the o-NH3(1_0-0_0) line (and, simultaneously, also of the o-H2O(1_10-1_01) transition) that will allow us to identify both similarities and differences between the physical and chemical conditions before and after the formation of a warm/hot source inside the dusty core identified in the SPIRE/PACS maps. Hence, these observations will improve our knowledge of the earliest phases in the evolution of high-mass stars. We will also attempt the detection of the NH(1-0) line towards a smaller sample of sources, in order to improve our knowledge of the N-chemistry during early high-mass star formation.

### SPECSO: Spectroscopy of Shocks in Outflows

Proposal ID: OT2_mbenedet_1

Principal Investigator: Milena Benedettini

Time: 26.6 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

In the early protostellar stages, fast jets powered by the nascent star, possibly surrounded by a wider angle wind, are seen to interact with the parental medium through molecular bowshocks, producing a slower moving molecular outflow cavity. The nature of the shock accelerating the outflow plays an important role in the dynamical and chemical evolution of the entrained gas.

We propose to study with Herschel the physics of protostellar outflow shocks from the observation of CO and OI lines with HIFI and PACS, in a broad sample of outflows.

These observations will permit to bring strong constraints to shock models over a wide range of parameters, and will facilitate the interpretation of current observational programs on protostellar shock chemistry and dynamics.

### Investigating the origin of the intercluster medium in M15

Proposal ID: OT2_mboyer_1

Principal Investigator: Martha Boyer

Time: 5.8 hours priority 1

Category: Galactic Other

Summary:

M15 (NGC 7078) is, quite possibly, the most unusual Galactic globular cluster. It is among the most metal-poor clusters ([Fe/H] = -2.4), yet has an extremely dusty environment. M15 is home to a dusty planetary nebula (PN), one of only four in a globular cluster, and is the only globular cluster with a dusty intercluster medium (ICM). Dust is expected to collect in globular clusters when mass-losing evolved stars eject material towards the end of their lives, but it is unclear why only M15 has been able to retain this ICM. It is possible that the dust originates in the Milky Way, as either swept-up or chance superimposed material. We propose to (1) image M15 with PACS and SPIRE to determine the ICM (and PN) dust temperature and mass, and (2) obtain PACS line spectroscopy of [C II] at 158 microns to determine whether the ICM is of Milky Way origin. These observations allow us to probe the nature of the ICM material, determine how long it has been collecting (or how quickly it is being removed), and rule out whether the material is instead from the Milky Way. The results will have broad implications for the presence of ICM in other globular clusters; if the ICM is found to be of Galactic origin, it will significantly weaken the case for ICM to be present in any globular cluster.

### Determining the evolutionary state of the young protostar Chamaeleon MMS1

Proposal ID: OT2_mcordine_3

Principal Investigator: Martin Cordiner

Time: 10 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

This proposal aims to determine the physical structure and evolutionary status of the relatively little-studied young protostar Chamaeleon MMS1. The central source has an unusually low luminosity and is embedded in an extremely chemically-rich parent cloud. It has been put forward as an example of a first hydrostatic core, but there is some disagreement in the literature as to whether or not it drives an outflow, and it may be undergoing episodic mass-accretion. Our proposed HIFI and PACS observations of CO and H2O rotational emission lines with a range of upper-state energies will probe the density and temperature structure of the envelope and, through radiative transfer/excitation analysis, will provide crucial information on the physical state of this object. Line profiles will be used as a probe of the envelope and outflow kinematics. OI 63 micron line mapping will provide information on the envelope energetics and will test for the presence of a hidden jet. SED measurements will help to characterise the central radiation source, disk and envelope. These combined observations are expected to improve our understanding of the earliest stages of protostar evolution.

### HCl+ in the Interstellar Medium

Proposal ID: OT2_mdeluca_2

Principal Investigator: Massimo De Luca

Time: 8.8 hours priority 2

Category: Interstellar Medium/HII regions

Summary:

The identification of the key molecules in the interstellar chlorine chemistry has required nearly three decades. Herschel-HIFI observations have revealed H2Cl+ in absorption in various Galactic lines of sight, with abundances at least ten times higher than predicted.

Recently, the proponents have tentatively identified strong absorption signatures, observed with HIFI towards two sources, with the ground-state rotational transition 2P_3/2, J=5/2-3/2 of H35Cl+, an ion that has long been predicted to be a key intermediate, together with H2Cl+, in the chlorine chemistry of diffuse clouds.

The detection, corroborated by a good agreement between observations and models of expected opacity profiles, shows, like H2Cl+, abundances in excess with respect to the expectations.

All these findings stress the need for a revision of the chlorine chemistry and of the physical parameters at play in the environments where these molecules are found. The detection of HCl+ in other sources, especially if in combination with available observations of H2Cl+, would constitute a formidable constraint for the models. The planned observations would then have an impact, not only on the chemistry, but also on our knowledge of the Interstellar Radiation Field, of the dust opacity profile and on atomic physics parameters.

We propose to observe this HCl+ transition with HIFI towards strong continuum sources for which several molecular tracers are already available, allowing us to clarify the environment where this ion is found.

The need for Herschel is extremely compelling, since the proposed transition, the only one reasonably detectable in the ISM for this species, is in a frequency range where a strong atmospheric O3 line would complicate any attempt of observation even for the Stratospheric Observatory SOFIA. This will thus be the last opportunity, perhaps in one decade or more, to observe this molecule that plays a fundamental role in the chlorine chemistry.

### A prototypical jet from an intermediate-mass protostar

Proposal ID: OT2_mdeluca_3

Principal Investigator: Massimo De Luca

Time: 13 hours priority 2

Category: Star Formation/Young Stellar Objects

Summary:

We ask for a joint effort of the three Herschel instruments to carry out an exhaustive spectroscopic study of the proto−stellar jet and of the molecular outflow driven by the source IRS20 (IRAS08479−4306), an intermediate-mass star precursor, in the Vela Molecular Ridge.

IRS20 constitutes a privileged target for being, at the same time, ordinary and peculiar. Ordinary because it is the most massive object at the center of a relatively small, young embedded cluster, within a cloud located on the Galactic Plane hosting Low− to Intermediate−Mass, likely quiescent, protostars. It is thus representative of the most common Intermediate−Mass star forming mode. Peculiar because the relatively short distance, the powerful, well resolved jet and outflow, the clear edge−on geometry of its disk, and the location outside the solar circle make it very easy to study.

Exploiting the spectroscopic capabilities of Herschel and the favorable displacement of the target configuration, these observations will allow a ful characterization of morphology and physical conditions of the jet and the outflow: we plan to obtain with PACS and SPIRE a wide line survey of the source surroundings, including several molecular (CO, 13CO, H2O) and atomic (OI, CII, NII) transitions, precious for deriving the physical conditions of the source vicinity, of the primary jet and of the outflowing gas; HIFI observations of the fundamental transition of the p−H2O line at higher spectral resolution are intended to resolve features that will guide in the interpretation of the lines not resolved by the other instruments. Combining these observations with data already available, from infrared to sub−mm, it will be possible to derive for the first time the mass ejection/mass accretion rate in an intermediate−mass star precursor.

The knowledge of the properties of this class of objects constitutes a crucial junction point for better understanding the modalities of the high−mass star formation.

### CH+ tomography of the central molecular zone

Proposal ID: OT2_mgerin_5

Principal Investigator: Maryvonne Gerin

Time: 16 hours priority 2

Category: Galactic Structure

Summary:

Herschel observations have revaled the diagnostic capabilities of hydrides, either ionized or neutral, easily detected in absorption against intense submillimeter sources. In this project, we propose to probe the diffuse molecular gas in the Galactic Center in the CH+ and CH ground state transitions. Pioneering work by Oka and collaborators have shown the existence of warm and diffuse gas (T~300K, n ~ 50 cm-3), uniquely probed by the H3+ infrared absorption lines. CH+ absorption observed by Herschel closely mimic the H3^+ line profiles towards nearby targets. As the number of stars available for IR spectroscopy is very limited, the spatial extend and dynamics of this new component is not known. We therefore propose to use CH+ as a complementary probe of this new component, using strong submillimeter sources as background targets for absorption. The CH+ observations will be complemented by CH spectra, as CH is a known tracer of diffuse molecular gas, and by 13CH+ spectra at selected positions.

### Molecular Outflows in Gas-Rich Mergers: The IR-Faint QSOs in the Final Merger Phase

Proposal ID: OT2_sveilleu_4

Principal Investigator: Sylvain Veilleux

Time: 37.2 hours priority 1

Category: Active galaxies/ULGs/QSOs

Summary:

The role of galactic winds in gas-rich mergers is of crucial importance to understand galaxy and supermassive black hole evolution. In the past year, our group has had three major scientific breakthroughs in this area: (1) The PACS discovery of powerful molecular OH winds in several ULIRGs, including Mrk 231. (2) The independent discovery from mm-wave CO interferometric observations in Mrk 231 of a spatially resolved molecular wind with estimated mass outflow rate ~4x larger than the star formation rate. (3) The detection from optical IFU observations of an equally powerful wide-angle neutral-gas outflow in this same object. These powerful outflows may be the long-sought "smoking gun" of quasar mechanical feedback purported to transform gas-rich mergers. Indeed, we see possible trends of increasing outflow velocities and decreasing depletion time scales with increasing AGN luminosities in our PACS data. The approved OT1 extension of this program to quasar-dominated ULIRGs will allow us to test these trends. However, by design, this sample does not contain any "classic" IR-faint QSOs in the critical late merger phases when the quasar has finally gotten rid of its natal cocoon and the effects of feedback are predicted to subside. So here we request 37.2h to obtain high-S/N OH 119 um spectra of 5 IR-faint quasar-dominated late stage mergers. We have a comprehensive set of multiwavelength data on all of these objects, including crucial spatially resolved optical neutral-gas absorption spectroscopy. We will look for trends between the basic measured properties of OH (incidence of absorption, kinematics, column densities) and host/evolutionary indicators. In cases of kinematic match between OH features and spatially resolved neutral-gas clouds, we will be able to infer the masses and kinetic energies of these outflows. Measured velocities in excess of ~1000 km/s or inferred mass outflow rates much larger than the star formation rates would be telltale signs of AGN-driven winds.

### Exploring the Dust Content of Galactic Winds with Herschel: The Dwarf Galaxy Population

Proposal ID: OT2_sveilleu_5

Principal Investigator: Sylvain Veilleux

Time: 38.1 hours priority 1

Category: Nearby galaxies

Summary:

We propose to extend our OT1 PACS imaging survey of galactic winds in nearby star-forming galaxies to the poorly explored but critically important low-mass end of the galaxy mass function. Following our OT1 strategy, we will obtain very deep PACS 70/160 micron data to map the detailed distribution of cold (T<100 K) dust in a small but representative sample of dwarf galaxies that are known to host outflows. These data will be compared to state-of-the-art, 3D numerical simulations of superwinds and predicted PACS fluxes. Direct and indirect evidence shows that dust is present on large (kiloparsec) scales in outflows in some starburst galaxies. However, this dust has never been mapped at wavelengths of 70-160 microns, and its geometry, mass, and energy are almost completely unknown. Recent spectacular SPIRE results on M82, as well as our own Spitzer IRAC 8-micron and MIPS 24-micron maps of the targeted wind galaxies, suggest that this survey will yield exciting new insights on the cold dust in these outflows. We will ascertain the significance of dusty superwinds in the context of outflow physics and the impact of the outflows on the host galaxies and the IGM. We will compare the distribution, mass, and energy of the cold dust to optical emission-line and absorption-line, mid-infrared, X-ray, and radio data compiled by us and other groups. As in OT1, we note that several of our targets are being mapped with PACS and SPIRE as part of key programs (KPs). However, the objectives of these programs are heterogeneous and often neglect the importance of outflow science. This is reflected in the depth of the observations at the critical shorter wavelengths, near the peak of the IR SED: the PACS KP data will not be able to detect the FIR emission expected from a M82-like wind in our galaxies. The proposed PACS survey will go nearly an order of magnitude deeper than the KP data and will complement the SPIRE portion of the KPs, while providing many advantages over the SPIRE data.

### Molecular Gas Flows in Active Galaxies of the Local Volume

Proposal ID: OT2_sveilleu_6

Principal Investigator: Sylvain Veilleux

Time: 35.3 hours priority 1

Category: Nearby galaxies

Summary:

Mechanical feedback from AGN-driven winds has been purported to play a central role in the evolution of galaxies. However, past searches for AGN winds have been heavily biased, selecting the brightest sources in bands affected either by obscuration and/or contamination from the host galaxy light, and incomplete, probing only the ionized gas phase of these winds. Remarkably, recent results from our group and others have demonstrated that the neutral and molecular components of AGN-driven winds often dominate the mass, and thus dynamics and energetics, of these winds. To address these limitations, we have been conducting an extensive multiwavelength campaign, including crucial spatially resolved optical neutral-gas absorption spectroscopy, of all AGN detected in the very hard X-rays (14-195 keV) by Swift-BAT. The Swift-BAT survey is the least biased all sky survey for AGN with respect to host galaxy properties and obscuration in the line-of-sight, and thus it is superior to past surveys for understanding the role of AGN-driven winds in galaxies. Here we request 35.3 hrs to obtain high-S/N OH 119 um spectra of all BAT-AGN within the Local Volume to characterize molecular gas in/outflows in these systems. A distance limit of <50 Mpc is selected to provide the best possible scale (<200 pc/arcsec) while also sampling the AGN luminosity function up to quasar-like values without favoring IR-bright systems due to the need for high-S/N data at ~120 um. We will look for trends between the properties of OH 119 um (incidence of absorption, kinematics, column densities), the AGN (e.g., luminosity, accretion rate), and the host (e.g., morphology, star formation rate, extinction). In cases of kinematic match between OH features and spatially resolved neutral-gas clouds, we will be able to infer the masses and kinetic energies of these flows. Measured blueshifted velocities in excess of ~1000 km/s or inferred mass outflow rates much larger than the star formation rates would be telltale signs of AGN-driven winds.

### Size is Not Everything: A PACS Emission Line Study of the Most Compact Infrared-luminous Galaxies

Proposal ID: OT2_tdiazsan_1

Principal Investigator: Tanio Diaz-Santos

Time: 45 hours priority 2

Category: Active galaxies/ULGs/QSOs

Summary:

Recent results based on far-infrared (IR) data obtained with Herschel strongly suggest the existence of two modes of star formation that apply to low and high-redshift galaxies: a quiescent mode for disks (or main-sequence galaxies) and a starburst mode probably associated with more efficient nuclear, compact star formation. This dichotomy implies that the properties of the inter stellar medium (ISM) in these two types of systems must be substantially different. We have used the mid- to far-IR colors of galaxies as a proxy for their compactness to select a sample of local, compact luminous IR galaxies ((U)LIRGs; LIR >= 10^11 Lsun) from the IRAS 12-micron sample. Our sample of 73 compact (U)LIRGs includes both Seyfert galaxies as well as purely star-forming systems, and therefore is not biased towards active galaxies only. We will observe the key far-IR [CII]158, [OI]63, and [OIII]88 micron emission lines with Herschel/PACS and use models of photo-dissociation regions (PDRs), shocks, X-ray dissociation regions (XDRs), and dusty AGNs to derive the main physical parameters of the ISM in this important class of systems, which are not being targeted by any Herschel project. Our proposed galaxy sample bridges the gap between other studies focused on the analysis of local galaxies with a range of IR luminosities, mid- to far-IR colors, or more spatially extended IR emission, providing a wider view of the star formation and nuclear activity in local IR-bright galaxies in extreme environments, and thus adding a significant contribution to the Herschel legacy. The total time requested for achieving this goal is 89.8 hours.

### The Synergy between Gas Dust and Star Formation for a Local Analog to z~1 Galaxy Evolution

Proposal ID: OT2_tjarrett_1

Principal Investigator: Thomas Jarrett

Time: 11.3 hours priority 2

Category: Low-z galaxies

Summary:

We require Herschel PACS and SPIRE to study the ISM and cold dust component of a gas-rich, local LIRG undergoing inside-out disk-building -- HIZOA J0836-42. Spitzer reveals this galaxy to be PDR-dominated with gas and stellar properties, as well as specific star formation, more in common with z~1 systems than local LIRGs. We see evidence of neutral gas funneling into the mid-IR star-forming disk. Our observations will provide crucial (and unique) spatial information of the ISM and cold dust that may be common to z~1 "scaled-up" disk galaxies that have large reservoirs of neutral gas that they are actively converting into stars, in an extended disk. Knowledge of the active enrichment and metamorphosis of the ISM further out in the disk due to "new" star formation will enable us to form a cohesive picture of this mechanism of star formation and the role of gas, dust and (old and new) stars. We will search for evidence of "dark" molecular hydrogen inhabiting PDRs and making a hidden (and potentially crucial) contribution to the molecular mass that fuel in these systems. We can achieve this by mapping the cool dust component across the HI disk and obtaining maps of the key cooling lines, [OI]63 and [CII]158. These data will be complementary to our broader multi-wavelength study, and motivate future planned observations that aim to address our main science goal: understanding how the components of star formation (gas, dust, stars) interact and drive the fundamental gas-to-stars evolutionary cycle for galaxies in the early universe.

### Probing the Star Formation and ISM Evolution in M33.

Proposal ID: OT2_tnikola_1

Principal Investigator: Thomas Nikola

Time: 12.5 hours priority 2

Category: Local Group galaxies

Summary:

We plan to investigate the interplay between the phases of the interstellar medium (ISM) and their evolution near star forming regions as a function of galactocentric distance by observing the far-infrared (far-IR) fine-structure lines of [CII] 158 micron, [OI] 63 micron and 146 micron, [NII] 122 micron,and [OIII] 88 micron in selected regions in the local-group galaxy M33. The transformation from atomic gas to molecular clouds and their subsequent destruction due to star formation is still poorly understood. Feedback from the young massive stars could heat the surrounding gas and thus hamper further star formation or compress the surrounding gas and thus increase the star formation effiency. The sequential evolution of cloud formation, star formation, and cloud destruction might depend on the internal as well as the external environmental conditions such as pressure, surface density, and metallicity, which change with galactocentric distance. The [CII], [OI], [OIII], and [NII] lines provide the best tools and M33 the optimal galaxy for this study. This proposal, for which we ask 12.5 hours observing time, is a follow-up project to the HerM33es key project.

### Herschel observations of dust processing in meger galaxies

Proposal ID: OT2_tonaka_6

Principal Investigator: Takashi Onaka

Time: 10.2 hours priority 2

Category: Nearby galaxies

Summary:

We propose to make PACS and SPIRE photometric mapping observations to obtain far-infrared (FIR) spectral energy distribution of the extended structures of the two merger galaxies NGC2782 and NGC7727, in which mid-infrared (MIR) observations with the Infrared Camera (IRC) onboard AKARI indicate the presence of PAH, and to investigate the dust processing associated with the merger event. Both galaxies show intriguing features at the mid-infrared band sensitive to the PAH features. The extended tail of NGC2782 seen at 7 micron is thought to have been produced by collision of a low-mass galaxy with the main galaxy about 200 Myr ago, while that seen in NGC7727 is a relic of the merger event of 1.2 Gyr ago. Both galaxies offer a unique opportunity to study dust processing in the merger event in different time scales. We propose to obtain FIR data to compare with the MIR data taken with the IRC, which will allow us to investigate the life cycle of dust grains in the ISM associated with violent events.

### A Rosetta Stone' for the cosmic X-ray and sub-mm backgrounds

Proposal ID: OT2_tshanks_3

Principal Investigator: Tom Shanks

Time: 9.4 hours priority 2

Category: Active galaxies/ULGs/QSOs

Summary:

We propose to measure FIR dust temperatures primarily for two X-ray absorbed, sub-mm bright, QSOs that may prove play the role of the Rosetta Stone' in relating the sub-mm and X-ray backgrounds. Of 15 Chandra X-ray QSOs in the central ~100 sq. arcmin of the William Herschel Deep Field (WHDF), Bielby et al (2011) found that the only 2 that are identified as sub-mm sources are these absorbed QSOs at z=1.33 and z=2.12, with the latter being a narrow-lined Type 2 QSO. 11 X-ray unabsorbed QSOs were all undetected by LABOCA at 870 microns. Similar results were found previously by Page et al (2004). On the other hand, Hatziminaoglou et al (2010) recently found that many unabsorbed QSOs are clearly detected at 24-500 microns indicating warmer dust temperatures. One possibility is that the presence of cold gas and cold dust are correlated. This would predict that absorbed QSOs may only contain cold dust and we propose to test this prediction via PACS and SPIRE observations. If more cold gas does imply more cold dust then the Compton-thick QSOs needed to explain hard X-ray background may also explain the sub-mm background.

### Herschel observations of nearby mergers: understanding the process of star-formation along cosmic time

Proposal ID: OT2_ulisen01_2

Principal Investigator: Ute Lisenfeld

Time: 18.5 hours priority 2

Category: Nearby galaxies

Summary:

We propose to observe a small sample of nearby major mergers in three different merging stages with Herschel PACS and SPIRE photometers. The observations will allow us to derive the dust surface density and from this the total gas surface density. Together with already available tracers of the SFR (Spitzer 24 micron and GALEX FUV) we can study the Kennicutt-Schmidt law. High resolution data of the atomic gas content (partly already available and partly applied for at the EVLA) allow us furthermore to make a distinction between atomic and molecular gas. The derivation of the total gas mass via the dust emission involves less serious uncertainties than the use of CO as a tracer of the molecular gas.

With these observation we aim to address the open question why merging galaxies form stars at about a 10 times higher rate compared to their gas mass than quiescent galaxies. Our recent numerical models explain this by a higher turbulence which make the step from low-density to high-density (star--forming) gas more efficient. It makes specific prediction about the efficiency of the conversion from atomic to molecular gas, which directly affects the ratio between SFR and gas mass, as a function of merger stage. The selection of our sample and the proposed observations will allow us to test the predictions of the simulations and provide therefore an opportunity to improve our understanding of the physical processes underlying star-formation and of the cosmic star formation history

### The Infrared View of Galaxy Evolution in the Environment of Groups: Unveiling the Dust

Proposal ID: OT2_vcharman_2

Principal Investigator: Vassilis Charmandaris

Time: 13.3 hours priority 2

Category: Low-z galaxies

Summary:

The so called Hickson Compact Groups (HCGs) occupy a unique position in the range of galaxy environments found in the local universe. While their density enhancements are high, close to those seen in rich clusters, the over-densities appear to be more locally contained. Dynamical interactions between the galaxies in the groups lead to consumption of the available gas, star formation, and a rapid evolution compared to field galaxies. It has been shown that HCGs contain significant amounts of dust, which has so far hampered a detailed understanding of those objects based on optical observations alone. Based on recent Spitzer observations, we have embarked in the first multiwavelength analysis of how groups affect galaxy evolution. We used the state-of-the-art theoretical models in order to interpret the complete spectral energy distribution of the galaxies from the UV to the IR, and compare them with samples of field galaxies and interacting systems. However, due to the proximity among the various galaxies in groups none of the past far-IR facilities (IRAS, Akari) had the angular resolution necessary to trace the far-IR emission of the individual group members, essential to determine the global energetics and dust content of the systems.

We propose to obtain deep broad-band far-IR images of 20 HCGs at various stages of evolution for which UV, optical, near-IR, and mid-IR data also exist. Herschel observations with their unique depth and high angular resolution, will enable us a) to accurately calculate the far-IR luminosity, dust mass and temperature of galaxies in HCGs in order to examine how the group environment affects them and b) determine the total "dust budget" in the groups by detecting the cold intragroup dust, studying its temperature, clumpiness, and spatial distribution. The proposed program requires a modest investment of 13.3 hrs.

### Star Formation and Molecular Gas in Distant Galaxies: SPIRE Spectroscopy of Quasar Absorption Systems

Proposal ID: OT2_vkulkarn_3

Principal Investigator: Varsha Kulkarni

Time: 28.9 hours priority 1

Category: Extra-galactic ISM

Summary:

Absorption line systems in quasar spectra, especially the damped Lyman alpha (DLA) and sub-DLA absorbers, provide excellent venues for directly studying the interstellar medium (ISM) in distant galaxies, selected independently of the galaxy luminosities. DLAs/sub-DLAs provide most of the neutral gas reservoir for star formation at high redshifts. A few especially cold, dusty absorbers have been discovered using radio surveys and the Sloan Digital Sky Survey. These absorbers, far richer in dust/molecules than the general absorber population, give us rare opportunities to probe molecular gas and star formation at high redshift. Unfortunately, very few sub-mm observations exist for these unique quasar absorbers. Here we propose SPIRE spectroscopy of 5 quasars with strong absorbers that appear to have cold/dusty gas. The proposed data will efficiently cover a wide spectral range that is expected to be rich in transitions of many atomic and molecular species (e.g., C I, N II, CH+, CO, 13CO, C18O, H2O) at the absorber redshifts. These transitions will allow us to estimate molecular abundances, and physical conditions of the absorber gas such as temperature and density. Comparisons of these distant absorbers with Milky Way ISM will provide a step toward understanding how ISM evolves with time. The molecular lines will also give constraints on isotopic ratios such as 12CO/13CO, and the cosmic microwave background temperature at the absorber redshifts. Our data will also cover the redshifted [C II] 158 micron emission line, which can help to constrain the star formation rate in the absorber galaxies. The proposed data will thus provide several fresh insights into the stellar and interstellar content of distant galaxies, and pave the way for future ALMA observations. Additionally, the data will provide important constraints on the continuum SEDs of the background quasars. Herschel SPIRE is the only current instrument that can offer the wavelength coverage needed to efficiently observe the lines of interest.

### Caught in the Middle: Post-Starbursts as Transitions from Ultraluminous Infrared Galaxies to Massive Ellipticals

Proposal ID: OT2_vwild_2

Principal Investigator: Vivienne Wild

Time: 9.7 hours priority 2

Category: Active galaxies/ULGs/QSOs

Summary:

One of the outstanding tasks in modern astrophysics is to uncover the physical mechanisms responsible for the observed tight correlation between super massive black hole mass, and host galaxy bulge mass and stellar velocity dispersion (M_BH-sigma relation). Numerical simulations invoke major mergers and interactions between massive, gas rich galaxies to reproduce the observed relation, along with the ULIRG number density, QSO luminosity function, black hole mass function and mass density. However, observational evidence for these suggested scenarios is either unavailable or inconclusive.

Here we propose to measure the far-infrared continuum and line properties of a unique sample of massive, dusty, obscured AGN, to reveal whether they are the descendants of ULIRGs and progenitors of massive elliptical galaxies. These 12 galaxies contribute around 10% of the total black hole accretion rate summed over a complete sample of nearly 17,000 local (z<0.07) galaxies, and thus represent a significant channel for black hole growth in the Universe. Their optical continuum suggests they underwent strong starbursts between 0.35 and 1Gyr ago. Their nebula emission line strengths, combined with a simple empirical model for the rate of decay of star formation following a starburst, predicts FIR luminosities during their starburst phase of 7e11-2e12 Lsun, implying that these were ULIRGS in the past. Herschel PACS+SPIRE observations will reveal whether this sample of unusual, dusty AGN is the much sought after transition'' phase between merger/ULIRG/starburst and elliptical galaxy.

### Extremely-metal poor galaxies: mapping dust emission

Proposal ID: OT2_yshi_3

Principal Investigator: Yong Shi

Time: 16.1 hours priority 1

Category: Nearby galaxies

Summary:

The understanding of the interstellar medium (ISM) and star formation in the low-metallicity environment is crucial to constrain formation of stars and galaxies of the first generation. The local extremely low-metallicity galaxies (XMPGs) with Z<Zsun/20 offer the unique laboratory with nearly metal-free environment that mimics the condition in the early universe. Previous infrared studies have focused on their integrated properties due to their small sizes and faint brightness. The general conclusion is that they show dramatic different ISM and star formation properties from more metal-rich galaxies, and that a large diversity in the properties is also seen among XMPGs alone. The high resolution combined with its multiple far-IR bands of Herschel will revolutionize the study of ISM and star formation in XMPGs through the spatially-resolved images of dust properties (mass and temperature) and SFRs. By relating the dust and star formation properties to the local physical conditions, we can start to understand the underlying physical mechanisms that regulate ISM and star formation processes in the extremely low-metallicity environment. We propose to obtain deep map of the dust emission in three XMPGs with Herschel PACS and SPIRE photometer. These three objects are carefully selected to facilitate the spatially-resolved study, i.e. the large size and previous IR detections by Spitzer. Combined with a rich ancillary data, we will (1) model dust emission to derive dust properties and then relate it to the local physical properties; (2) derive reliable SFRs by combining IR-based obscured SFRs and UV-based unobscured ones, from which we then can understand the star formation processes at sub-kpc scales.

## Cosmology (56)

### CACHE: the Comprehensive ACT Cluster Herschel Experiment

Proposal ID: OT2_abaker01_2

Principal Investigator: Andrew Baker

Time: 30 hours priority 2

Category: Galaxy clusters/Lensing clusters

Summary:

We propose deep five-band imaging with SPIRE and PACS of 10 of the most massive galaxy clusters in a 455 square degree southern strip surveyed by the Atacama Cosmology Telescope (ACT). Our targets lie at 0.3 < z < 1.1 and were identified by their 2mm Sunyaev-Zel'dovich Effect (SZE) decrements, which provide a redshift-independent mass selection, and confirmed with optical imaging. Herschel observations, building on X-ray, optical, near-IR, submillimeter, and radio data, will allow us to study how star formation within individual galaxy members and integrated across clusters is influenced by the process of cluster assembly in the most massive systems out to z ~ 1. We will also extract our targets' SZE decrement/increment spectra and mass profiles, providing useful inputs to the cross-calibration and interpretation of large SZE surveys. Finally, our observations will exploit the clusters' gravitational lensing for the detection of dusty background galaxies, down to flux levels that would otherwise be below the confusion limit of blank-field imaging. By combining PACS and SPIRE data with our ancillary observations, we will be able to determine photometric redshifts for these background galaxies sufficiently well to allow followup observations with ALMA, for which our fields' southern declinations are ideal, in order to understand the detailed physical properties of dusty star-forming galaxies at high redshift.

### A large-scale filament of IR-bright galaxies at redshift 0.23

Proposal ID: OT2_abiviano_1

Principal Investigator: Andrea Biviano

Time: 18.1 hours priority 2

Category: Galaxy clusters/Lensing clusters

Summary:

Large-scale filaments are home to about 1/3 of all galaxies in the universe. Their characteristics make them ideal environments for galaxy-galaxy mergers and interactions, leading to bursts of star-formation, visible in the infra-red (IR). So far, only a few studies of filament galaxies exist, and even fewer including mid- or far-IR observations. We propose to partially fill this gap in our knowledge of galaxy evolution by observing a 14 Mpc long filament of galaxies connecting two clusters at redshift 0.23, with PACS and SPIRE for a total time of 18.1 hours. Complemented with already available extensive optical spectroscopic (1413 galaxies) and multiwavelength photometric data (including mid-IR data from Spitzer for one cluster and part of the filament), the new Herschel data will allow us to determine the galaxy (specific) star-formation rates as a function of their location in the filament with respect to the two clusters. This will help constraining which physical processes are responsible for the excess of star-forming galaxies in the filament relative to both denser and less dense galaxy environments, discovered in our previous studies of this region (Fadda et al. 2008, Edwards et al. 2010a,b, Biviano et al. 2011).

### The Local Galaxy Clusters Environmental Survey

Proposal ID: OT2_acava_2

Principal Investigator: Antonio Cava

Time: 20.6 hours priority 2

Category: Galaxy clusters/Lensing clusters

Summary:

The star formation activity in a present-day galaxy is strongly correlated with the environment in which the galaxy lives. Passive, spheroidal systems are preferentially found in the core of clusters, whereas star forming, late-type galaxies inhabit low-density environments, from the field to the outskirts of clusters. Therefore, galaxy clusters are the best places where to probe galaxy transformation. Different mechanisms can contribute in driving galaxy transformations by depleting the galaxy of its cold gas reservoir and decreasing the star formation activity. Ram pressure stripping, harassment and galaxy-galaxy collisions are likely to play a role but it is still unclear which of these are the dominant mechanisms driving galaxy evolution inside clusters. In the continuos gold rush toward the highest redshift galaxies the local environment has long been neglected. In this proposal we aim to study the star formation activity and the galaxy dust role in nearby galaxy clusters (0.04<z<0.07) as a function of environment by probing the broadest possible range of environments from the core of rich clusters to the outskirts, where the main processes modifying galaxy properties occur.

### The ISM content and the SF History of Two Clusters with Very Distinct Environments at z=0.2: Abell 963 vs. Abell 2192

Proposal ID: OT2_achung_3

Principal Investigator: Aeree Chung

Time: 40.3 hours priority 2

Category: Galaxy clusters/Lensing clusters

Summary:

We propose to image 1 sq. degree regions centered on Abell 963 and Abell 2192 in PACS/SPIRE parallel mode. These two galaxy clusters have very distinct environments yet both are located at z~0.2, where the Butcher-Oemler effect (the fraction of blue galaxies near the cluster center increases with redshift) begins to show. To identify physical mechanisms driving galaxy evolution in clusters at this redshift, our team initiated a multi-wavelength study of Abell 963, a rich cluster with a high fraction of blue galaxies around z~0.2, and Abell 2192, a less massive cluster with a low dispersion at a similar redshift. With the goal of relating the star formation activity with the ISM content, we have obtained deep WSRT HI imaging data, which is unique to date at this redshift. Besides HI data, we have collected radio continuum, mid infrared, optical, and UV data to diagnose the ISM removal processes and to study detailed star formation histories. In addition, we will start a CO survey of the two clusters in the near future to measure the total cool gas mass. Our multi-wavelength survey area is large (> 10 Mpc in diameter on the sky) enough to include low-density environments where galaxies appear to undergo significant evolution. The Herschel data will allow us to map out the entire IR SED of various galaxy populations and also to study dust properties, which is essential for this study. We request 40.3 hrs of Herschel time to obtain 9 PACS/SPIRE scans over 1 sq. degree field centered on each cluster (18 scans in total) to achieve the enough sensitivity to detect L* galaxies in each cluster.

### The most active AGN in the cores of clusters of galaxies

Proposal ID: OT2_aedge_6

Principal Investigator: Alastair Edge

Time: 8.4 hours priority 2

Category: Galaxy clusters/Lensing clusters

Summary:

In massive galaxies the AGN at the core can have a profound effect on its host galaxy from their formation to the present day. This effect is particularly important in the cores of clusters of galaxies where the AGN is believed to be strongly suppressing the cooling of the hot intracluster gas that surrounds the brightest cluster galaxy (BCG). We propose to obtain PACS photometry and spectroscopy of four BCGs that have strong AGN characteristics ([OIII] line, MIR continuum and/or flat spectrum radio continuum). These four systems are the most extreme BCGs selected from a sample of over one thousand X-ray selected clusters and hence can be used to constrain the energetics and duty cycle of AGN in a statistically meaningful sample of clusters. The Herschel data will reveal important diagnostics of the individual AGN that can be applied to weak AGN in the larger sample.

### Tracing the Evolution of Star Formation Activity in High Redshift Galaxy Clusters

Proposal ID: OT2_apope_3

Principal Investigator: Alexandra Pope

Time: 54.7 hours priority 1

Category: Galaxy clusters/Lensing clusters

Summary:

Recent observations suggest a reversal in the star formation rate density relation at z>1 such that the average star formation rate in galaxies increases with increasing local galaxy density. Two high redshift clusters have shown an increased fraction of actively star forming galaxies towards the center of the cluster, albeit with small number statistics, but the epoch at which this transition occurs is poorly constrained. We propose a statistical study of the dust−obscured star formation activity in a mass-limited sample of 11 spectroscopically-confirmed clusters from z=1.1-1.8 with PACS imaging at 100/160 microns. With 54.7 hours of observing time, we will detect ~150 cluster galaxies down to 100 solar masses per year and many more field galaxies. Our sample spans the fundamental redshift range during which massive clusters show signs of transitioning from a stage of active formation to passive evolution. We will determine the role of the cluster environment on the evolution of infrared luminous galaxies as a function of redshift. These Herschel observations will allow us to map out the star formation activity in galaxy clusters and constrain their mass assembly epoch.

### Star formation in proto-clusters

Proposal ID: OT2_baltieri_5

Principal Investigator: Bruno Altieri

Time: 5 hours priority 1

Category: High-z galaxies

Summary:

Massive clusters of galaxies have been found to date from as early as 3-4 billion years after the Big Bang. Cosmological simulations using the current cold dark matter model predict that these systems should descend from 'proto-clusters' - early overdensities of massive galaxies that merge hierarchically to form a cluster. These protocluster regions themselves are built up hierarchically and so are expected to contain extremely massive galaxies, progenitors of the quiescent behemoths observed in cores of the present day massive galaxy clusters. Observational evidence for this picture, however, is sparse because high-redshift proto-clusters are rare and difficult to observe. Here we propose to probe with Herschel SPIRE the very beginning of the cluster and massive galaxies formation process by observing 5 proto-clusters at 3<z<4. The aim of the project is to observe the entire Ultraluminous IR galaxy (ULIRG) population, dominating the bulk of the star formation at such high redshift, to compare the properties of the proto-cluster galaxies with those of field galaxies at similar redshift. Determining whether cluster galaxies differ from field galaxies when the proto-cluster was still forming, tells us whether any of the difference observed today is driven by nature as apposed to nurture.

### Through the Dusty Glass: Using Herschel to Improve Measurments of Dark Energy

Proposal ID: OT2_btucker_2

Time: 57.5 hours priority 2

Category: High-z galaxies

Summary:

We propose to measure the dust properties and far-iR star formation rates (SFR) of high redshift type Ia supernova (SN Ia) host galaxies to improve their use as cosmic probes. In fitting SN Ia light curves, we must fit both the intrinsic color variation of the SN and dust together, limiting their statistical precision. Using light curve fitting, SN Ia have been observed to have a wide range of dust values and laws, some that are very different from the Milky Way. Additionally, after correction, SN Ia light curves show a dependency on their ultraviolet (UV) specific SFR's (sSFR), however the UV is sensitive to dust and thus our UV SFRs might be underestimated. We propose to take PACS and SPIRE observations of 74 high redshift host galaxies of SN Ia discovered by the ESSENCE project. We will measure the dust mass and temperature, using this information to re-analyze SN Ia light curves and study their intrinsic properties. We will also measure the far-IR SFRs to look for correlations and dependancies of SN Ia's on their host galaxies. All of this information will be used to improve and refine our measurements of Dark Energy.

### A Herschel Study of WISE Discovered Lyman-alpha Blobs: The missing link?

Proposal ID: OT2_cbridg01_1

Principal Investigator: Carrie Bridge

Time: 5.6 hours priority 1

Category: High-z galaxies

Summary:

Using data from the NASA Wide-field Infrared Survey Explorer (WISE) mission coupled with deep optical spectroscopy, we have discovered a new population of dusty z~2 galaxies surrounded by large spatially extended Lyman-alpha emission (40-100kpc). These galaxies have redder mid-IR colors than any other high-z dusty populations, inferred IR luminosities of L_FIR>10^13, are unlensed, and are experiencing intense AGN/supernova feedback. These unique properties, and rarity on the sky, make them strong candidates for being one of the missing links'' in the evolution of massive ellipticals. They have opened up a new regime where spatially extended Ly-alpha and large amounts of dust are likely linked at the key transition from a dusty starburst to a QSO.

We request 5.6 hours to obtain Herschel-PACS and SPIRE imaging of *all* 18 spectroscopically confirmed WISE Ly-alpha blobs. Herschel is the only facility that fully probes the peak of the bolometric emission at this redshift. These observations are required in order to 1) derive precise FIR luminosities 2) place robust constraints on the starburst and AGN components 3) study how feedback effects the shape of far-IR seds at high-z 4) uncover what is driving the winds responsible for powering the Ly-alpha clouds around these dusty galaxies and 5) place this new class of extreme object in context with the other well studied z~2 dusty galaxies.

### A Fine-Structure Line Survey of SMMJ02399

Proposal ID: OT2_cferkinh_1

Principal Investigator: Carl Ferkinhoff

Time: 10.7 hours priority 2

Category: High-z galaxies

Summary:

We propose to continue our study of the high-z galaxy SMMJ02399-0136 at z=2.8 by observing with Herschel several bright far-IR fine-structure lines from O, N, and C, as well as its rest-frame mid- and far-IR continuum. This source is an excellent target of study because it has been extensively observed in other wavelengths, we have previously detected it in the [NII] 122 and [OIII] 88 micron lines, using ZEUS on the CSO, and it resides in the epoch of peak star formation in the Universe. Furthermore, SMMJ02399 is a multi-component system with AGN and starburst components at different relative velocities. Thus it presents the unique opportunity of observing an AGN, a starburst, and their interaction simultaneously from a source at high-z. The sensitivity, resolution, and broad spectral coverage of Herschels spectrometers, makes Herschel the ideal observatory from which we can make these observations. For several lines, it is the only observatory capable. Our proposed Herschel observations will allow us to determine the AGN and starburst contribution to the lines, characterize the starburst and the narrow-line region of the AGN, and explore the relationships between star formation and AGN in galaxies in the early universe.

### A z=1-2 oxygen survey. II. PAH-selected star forming and AGN sources

Proposal ID: OT2_dbrisbin_1

Principal Investigator: Drew Brisbin

Time: 27.6 hours priority 1

Category: High-z galaxies

Summary:

We are conducting a survey of the [CII] 158um line from galaxies at redshifts 1-2 using our grating spectrometer, ZEUS on the CSO. Our first 13 galaxy survey showed that luminous star forming galaxies in this epoch have moderate intensity kpc-scale star formation – likely an extension of the Schmidt-Kennicutt law to very high gas mass fractions. Our AGN dominated systems have similarly large scale, but significantly more intense star formation suggesting punctuated, collision-induced star formation. We were awarded OT1 PACS spectroscopy and PACS/SPIRE photometry of these sources to observe the oxygen [OI], [OIII], and [OIV] fine-structure lines and far-IR continuum to characterize the star formation and AGN activity in these sources. Only two of our sources have been observed to date, but with good astrophysical success. Since the OT1 submission, we have detected 11 more z ~1-2 sources in [CII] with ZEUS. Here we propose an OT2 oxygen line/far-IR continuum study for 10 of these new sources. The new source list significantly enhances our OT1 survey in that (1) we nearly double our sample greatly increasing statistical significance of the results (2) the new group includes 7 Spitzer/PAH sources. PAH emission arises from PDRs tracing the photo-electric heating, while the [CII] and [OI] lines trace the cooling. PAHS therefore trace star formation and, since the features are extremely bright, are excellent redshift indicators. Future missions (e.g. JWST and SPICA/SAFARI) will rely on PAH spectroscopy at high z. It is therefore vital to study PAH emission and its relationship to star formation. The proposed work explores this connection at redshifts 1-2, near the peak of star formation per unit co-moving volume over cosmic time. In this interval ZEUS and PACs share a great synergy with well-matched sensitivities enabling detections of [CII] and oxygen in a wide variety of systems.

### Following the evolution of infalling galaxies onto the cluster Abell 85

Time: 21.4 hours priority 2

Category: Galaxy clusters/Lensing clusters

Summary:

We propose to observe with PACS and SPIRE the unique system of Abell 85: a rich cluster with a feeding filament detected in the X-ray. Through extensive optical spectroscopy, we already detected an overdensity of star-forming galaxies along the filament. Infrared observations, in conjuction with newly obtained GALEX data, will allow us to obtain a complete census of the obscured and unobscured star forming activity along the filament and inside the cluster. Since galaxies are infalling onto the cluster along the filament, this corresponds to studying the different stages of evolution of galaxies during the infall. Moreover, due to the vicinity of the cluster (z=0.055), we will obtain images deep enough to detect dwarf galaxies, those most affected by the environment for which we expect the largest variations in specific star formation.

### A wide and deep far-infrared galaxy evolution survey of the Extended Groth Strip

Proposal ID: OT2_dlutz_5

Principal Investigator: Dieter Lutz

Time: 150.7 hours priority 2

Category: High-z galaxies

Summary:

We propose a deep and wide PACS 100 and 160micron survey of the Extended Groth Strip (EGS) region, providing an area/depth combination that is unique to Herschel deep fields and leveraging the excellent existing multiwavelength database for this field from AEGIS, CANDELS, Fidel, GTC, IRAM PdB, and other projects. With unprecedented statistics, our observations will probe calorimetric' star formation rates based on the rest frame far-infrared SED peak, down to galaxies on the z~1 main sequence. We will characterise scalings between star formation rate, stellar mass, gas mass, dynamical mass, morphology, metallicity of typical z~1 galaxies. EGS is unrivaled for study of the effects of galaxy environment. The deep Herschel data in combination with the unique Chandra coverage for a field of this size will permit to study star formation in AGN hosts in a luminosity and redshift regime where previous results give tantalising evidence for a transition between secularly evolving hosts and more violent short term effects, but where previous Herschel datasets are limited in either statistics or depth. Beyond these two core science questions, the combination of the new Herschel data, with an estimated 3000-4000 sources, and the rich EGS multiwavelength database will permit a broad range of legacy galaxy evolution studies and provide a lasting archival value.

### Far Infrared Spectroscopy in a High Redshift Galaxy Sample

Proposal ID: OT2_dmarrone_2

Principal Investigator: Daniel Marrone

Time: 76.6 hours priority 2

Category: High-z galaxies

Summary:

Imaging surveys have identified and counted a major population of very bright, massive, dusty galaxies at high redshifts. To understand the astrophysics of this population, i.e., how they generate their luminosities, requires Herschel spectroscopy of their strong diagnostic FIR fine-structure emission lines. The very large sky area surveyed by SPT provides a unique sample of such galaxies at z=2.5-6, i.e., viewed when the Universe was only 1-2 Gyrs old. They are especially bright, and therefore suitable for spectroscopy, because gravitational lensing has magnified them by 10-30 times. We propose a 2-pronged program of PACS and SPIRE spectroscopy to measure the full range of ISM ionizations, from OI, to OIII and in some cases OIV, in 17 dusty, young galaxies. The resulting line ratios will provide the first quantitative estimates of the emission from star formation, PDRs, and a possible AGN, independent of absorption. (In some galaxies, our proposed spectroscopy may be sensitive enough to detect OH lines in either absorption or emission).

### A survey of the host galaxies of dust-obscured gamma-ray bursts

Proposal ID: OT2_dperley_1

Principal Investigator: Daniel Perley

Time: 36.7 hours priority 2

Category: High-z galaxies

Summary:

We propose to conduct a survey of the host galaxies of dark gamma-ray bursts (GRBs), events whose optical afterglow flux was severely diminshed by dust within their host galaxy (and which historically have been significantly under-represented in host catalogs). Our multi-year campaign of ground- and space-based follow-up has shown that these galaxies are much redder, more luminous, and generally more diverse than ordinary GRB host galaxies, making them promising candidates for long-wavelenength follow-up. Ground-based searches for radio and submillimeter emission have so far been fruitless - yet if GRBs are indeed representative of the sites of high-redshift star-formation, large far-IR luminosities are expected for some GRB hosts. By observing at the dust emission peak, PACS is particularly sensitive to dust reradiation and is relatively unaffected by variations in dust temperature, making it ideal for finding and characterizing this elusive emission. Our PACS observations will measure or tightly constrain the far-IR luminosity and dust temperatures of many dark GRB hosts and thereby calculate the total star-formation rate and obscuration fraction of this sample. These observations, combined with our large ground- and space-based optical/NIR/MIR observing programs, will definitively reveal to what extent the obscuration properties and bolometric luminosities of dark GRB hosts resemble those of ordinary GRB hosts and of star-forming galaxy populations generally, and evaluate in detail the use of GRBs as high-z star-formation tracers. Our sample has been carefully chosen to ensure all targets are heavily dust-obscured GRBs (and not simply underluminous or poorly-observed); to represent the full range of diversity seen among dark GRB host galaxies; to have excellent existing multiwavelength follow-up with other instruments; and to optimize the detectability of the sample to Herschel, even in the pessimistic case that GRB hosts harbor little highly dust-embedded star formation.

### Does the Most Distant Starburst Galaxy Host an AGN?

Proposal ID: OT2_driecher_3

Principal Investigator: Dominik Riechers

Time: 3.9 hours priority 1

Category: High-z galaxies

Summary:

In our deep, "blind" wide-band millimeter spectroscopic follow-up campaign on HerMES Herschel/SPIRE sources, we have recently made a spectacular discovery. Based on the secure identification of a suite of atomic fine structure and molecular lines, we have discovered Herschel's "first-born" starburst, a submillimeter galaxy at an unprecedented redshift of z=6.34, when the Universe was only 885 million years old. This source, dubbed FLS3, has a 250um to 20cm spectral energy distribution (SED) comparable to lower redshift starbursts (in the rest frame). However, due to its extreme redshift, the blue wing of the SED below 250um (rest-frame 34um) is only poorly constrained. This prevents investigations of the potential presence of warm, >100K dust associated with a dust-enshrouded, optically faint active galactic nucleus (AGN), for which there may be tentative evidence in the extensive, panchromatic dataset we were able to assemble on this source over the past three months. PACS photometry is perfectly suited to remedy this unfortunate gap in our wavelength coverage, as it covers the rest-frame 8-29um range - ideal to investigate the presence of warm dust associated with an obscured AGN. The proposed, inexpensive study (only 3.9hr of PACS photometry) will offer us a first glimpse into the science that SPICA will enable in the very early Universe at the end of this decade.

### Herschel Lensing Survey II: Completing the Herschel Legacy with the HST/MCT CLASH Sample

Proposal ID: OT2_eegami_5

Principal Investigator: Eiichi Egami

Time: 48.2 hours priority 1

Category: High-z galaxies

Summary:

For deep imaging longward of 100 um, confusion noise sets the fundamental sensitivity limits achievable with Herschel, and these limits cannot be improved by integrating longer. To penetrate through this confusion limit and detect faint high-redshift galaxies, gravitational lensing by massive galaxy clusters offers a very powerful and yet cheap solution. For this reason, our team has been conducting a PACS/SPIRE imaging survey of 44 massive lensing clusters as one of the Herschel Key Programs, "The Herschel Lensing Survey" (PI: Egami, 292.3 hrs). Deep PACS/SPIRE imaging data of massive clusters are quite rich with a variety of information, which allows us to study not only the properties of gravitationally lensed high-redshift galaxies but also those of cluster member galaxies and the intracluster medium through the analysis of the Sunyaev-Zel'dovich effect.

In January 2010, a massive HST program targeting powerful lensing clusters was accepted as one of the three multi-cycle treasury (MCT) programs. This program, the Cluster Lensing And Supernova survey with Hubble'' (CLASH), has an allocation of 524 orbits, and will obtain deep ACS and WFC3 images of 25 massive galaxy clusters using 16 broad-band filters from near-UV (2250 A) to near-IR (1.6 um). These extensive multi-filter imaging observations will produce high-precision photometric redshifts (sigma/(1+z)<0.02). On average, the program spends 20 orbits per cluster. Considering this enormous investment of HST time, the CLASH program will define the ultimate sample of massive galaxy clusters on which future studies will focus.

Here, we propose to obtain deep PACS and SPIRE images for 10 CLASH clusters that still lack such data (the other 15 clusters already have a good Herschel coverage). To fully exploit the combination of the Herschel and HST data, the HLS and CLASH teams are submitting this proposal jointly with the participation of key scientists from both teams.

### SPIRE Snapshot Survey II: Using SPT/CODEX Massive Clusters as Powerful Gravitational Lenses

Proposal ID: OT2_eegami_6

Principal Investigator: Eiichi Egami

Time: 25 hours priority 1

Category: Galaxy clusters/Lensing clusters

Summary:

On the extragalactic side, one of the most remarkable results coming out of Herschel is the discovery of extremely bright (>100 mJy in the SPIRE bands) gravitationally lensed galaxies. The great sensitivity and mapping speed of SPIRE have enabled us to find these rare extraordinary objects. What is truly exciting about these bright lensed galaxies is that they enable a variety of detailed multi-wavelength follow-up observations, shedding new light on the physical properties of these high-redshift sources. In this regard, our OT1 program, "SPIRE Snapshot Survey of Massive Galaxy Clusters" turned out to be a great success. After imaging ~50 galaxies out of 279 in the program, we have already found two spectacularly bright lensed galaxies, one of which is at a redshift of 4.69. This type of cluster-lensed sources are not only bright but also spatially stretched over a large scale, so ALMA (or NOEMA in the north) is likely to be able to study them at the level of individual GMCs. Such studies will open up a new frontier in the study of high-redshift galaxies.

Here, we propose to extend this highly efficient and effective survey of gravitationally lensed galaxies to another 353 clusters carefully chosen from the SPT and CODEX cluster samples. These samples contain newly discovered high-redshift (z>0.3) massive (>3-4e14 Msun) clusters, which can be used as powerful gravitational lenses to magnify sources at high redshift. With the OT1 and OT2 surveys together, we expect to find ~20 highly magnified SPIRE sources with exceptional brightnesses (assuming a discovery rate of ~1/30). Such a unique sample of extraordinary objects will enable a variety of follow-up sciences, and will therefore remain as a great legacy of the Herschel mission for years to come.

### Unique FIR Signature of Quenched Star Formation in Super Group Abell 1882

Proposal ID: OT2_gmorriso_2

Principal Investigator: Glenn Morrison

Time: 5.1 hours priority 2

Category: Galaxy clusters/Lensing clusters

Summary:

A unique MIR/FIR signature of quenched star formation (SF) in early-type cluster galaxies has recently been discovered. This demise of active SF apparently imprints itself on the MIR (powered by SF) and FIR (powered in part by ISM radiation field) dust emission for a period of only ~few x 10^7yr. If true, this signature could be used as a marker of quenching SF and the location, hence mechanism(s) used to extinguish that final SF episode in cluster S0s, be determined. However, without FIR data it is unclear if this signature is from the lack of SF or unusually cold dust.

Our ongoing study of Abell 1882, a coalescing supergroup observed just prior to collapsing into a rich cluster, has uncovered a significant population of these galaxies. We request Herschel PACS and SPIRE observations of the supergroup Abell 1882 to validate the report of a unique MIR/FIR signature of star-formation quenching that is occurring in early-type galaxies. This 27.8hr Herschel proposal will add key knowledge to the formation process of S0 galaxies and for the member population as a whole, dust properties plus gas consumption time-scale in a supergroup in the act of forming a rich cluster.

### PACS Oxygen Spectroscopy of High Velocity [CII] Outflows in PG1206+459

Proposal ID: OT2_gstacey_6

Principal Investigator: Gordon Stacey

Time: 10.2 hours priority 1

Category: High-z galaxies

Summary:

We have discovered extreme velocity [CII] 158 um line emission from the z = 1.2 hyper-luminous QSO PG 1206+459. The [CII] line emission is concentrated in twin lobes of emission roughly centered on the CO emission but displaced +/- 1500 km/s with respect to the CO line core. The mass traced in the [CII] line is quite large - about 5E9 M(solar) in each lobe  or 13% of the total molecular gas mass in the host galaxy. We interpret this symmetric [CII] velocity structure as an outflow, likely driven by the AGN. The velocities of the [CII] lobes are larger than the escape velocity, so much of this material may leave the galaxy quenching both star formation and AGN activity, and transforming it into a "red-and-dead" passive galaxy. The CO line profile also shows a broad and blueshifted component that may represent an additional molecular component to the outflow, although a merger origin is also possible. In OT1 we were awarded 2.9 hours of PACS spectroscopy (not yet scheduled) to observe the [OI] 63 um, [OIII] 52 and 88 um, and [OIV] 26 um lines from the blue component of the line. Here we ask for an additional 10.2 hours of PACS time to widen our spectral scan to enclose the newly discovered (March 2011) red lobe and significantly improve our detection limit over the entire velocity range. These observations will be used to constrain the physical conditions, ionization structure, total mass, and radiative environment of the outflowing material using extinction-free probes. Our [CII] observations of PG1206 represent the first time that massive outflows have been detected in the [CII] line - a well established tracer of photodissociated molecular gas. The proposed Herschel observations will lay the groundwork for future studies of molecular outflows using [CII] and other far-IR lines in the early universe that will soon be possible with ALMA.

### Constraining the star-formation activity in very high-redshift clusters: Herschel observations of SpARCS clusters at z = 1.6

Proposal ID: OT2_gwilson_2

Principal Investigator: Gillian Wilson

Time: 36.8 hours priority 2

Category: Galaxy clusters/Lensing clusters

Summary:

We propose deep PACS 110/160 micron imaging for two of the most distant rich clusters ever discovered at z=1.6. These spectroscopically confirmed clusters are drawn from the homogeneously selected Spitzer Adaptation of the Red-sequence Cluster Survey (SpARCS), and have impressive spectroscopic coverage (a total of 26 confirmed members) and extensive multi-wavelength follow-up data (UV-MIR). This epoch marks a crucial turning point in the star formation rate-density relation: limited studies have shown that star formation shifts toward higher densities at z~1, and even peaks in a z=1.6 cluster core, albeit only a single cluster at this distance has been observed in the IR until now. Moreover, MIPS imaging has already identified nine cluster members, confirming that dust enshrouded star formation is occurring in these dense fields. We will use the PACS/MIPS data, in combination with the extensive optical spectroscopy and photometry, to characterize the nature of IR-luminous galaxies in clusters at z=1.6. We will also measure the total star formation rate in these clusters, which will be used to study the effect of environment on galaxy formation at an exciting new redshift regime.

### Constraining the star-formation activity in 10 SpARCS clusters: star-formation in the densest regions at z =1

Proposal ID: OT2_gwilson_3

Principal Investigator: Gillian Wilson

Time: 25.6 hours priority 1

Category: Galaxy clusters/Lensing clusters

Summary:

We propose deep PACS imaging at 110/160 microns of a unique sample of ten high-redshift galaxy clusters spanning 0.87<z<1.34. These rich clusters are drawn from the homogeneously selected Spitzer Adaptation of the Red-sequence Cluster Survey (SpARCS), and have impressive spectroscopic coverage (a total of 457 confirmed members) and extensive multi-wavelength follow-up data (UV-MIR). These clusters bridge a pivotal epoch when star formation shifts toward higher densities and when substantial cluster mass is assembled. Moreover, MIPS imaging has already identified 55 cluster members, confirming that dust enshrouded star formation is occurring in these dense fields. We will use the PACS/MIPS data, in combination with the extensive optical spectroscopy and photometry, to characterize the nature of IR-luminous galaxies in clusters at z~1. We will also measure the total star formation rate in these clusters, which will be used to study the effect of environment on galaxy formation.

### Revealing dusty starbursts around an X-ray emitting galaxy cluster at z=2.07

Proposal ID: OT2_hdannerb_1

Principal Investigator: Helmut Dannerbauer

Time: 3.9 hours priority 1

Category: Galaxy clusters/Lensing clusters

Summary:

We propose Herschel-SPIRE imaging of a 14'x14' field (corresponding to 7.1 Mpc x 7.1 Mpc) around the recently discovered cluster CL1449+0856 at redshift z=2.07. This structure is the most distant X-ray luminous galaxy cluster known to date, traced by a strong overdensity of red compact galaxies. Up to now, we securely identified 21 cluster members and our Spitzer-MIPS 24micron observations reveal a very high degree of star-forming activity in the cluster core. With our SPIRE imaging, we aim to reveal obscured star-formation activity within and around this evolved galaxy cluster as expected around a rapidly assembling high-z halo, as already indicated by our very recently obtained APEX-LABOCA imaging. We will search for massive dusty starbursts as cluster members, identify and characterize the counterparts of LABOCA SMGs, determine SEDs and dust temperatures of our sources and compare the properties of our IR-bright cluster members with SMGs in blank fields. This project will push the study of massive dusty starbursts in established clusters to the highest possible redshifts.

### Herschel unveils the nature of high-z (2<z<4) protocluster candidates selected by Planck

Proposal ID: OT2_hdole_1

Principal Investigator: Herve Dole

Time: 16.3 hours priority 1

Category: High-z galaxies

Summary:

The Planck mission has the unique capability of finding systematically and on the whole sky the rarest, most luminous high redshift submm sources. These can be lensed objects or proto-groups/clusters of galaxies containing many individual sources forming stars at very high rates.  Our full sample of candidates contains about 1 source per 30 sq. deg., and already 3 candidates have been confirmed as interesting high-z sources: one was found to be a proto-group at z~3, based on a SPIRE OT1 pilot project; and 2 others are z~3-4.6 sources already found in the H-ATLAS and around A773.  We now propose to use SPIRE to image a larger set of Planck sources to obtain a statistically significant sample of 70 high-z proto-groups and clusters.  This will give new insights into the early evolution of galaxies in the highest density regions, improving our understanding of the relationship between the growth of structures and star-formation, and placing constraints on the level of non-Gaussianity within the LCDM model.  This program exploits the exceptional synergy and complementarity between Planck and Herschel.

### Buried Engines: Exteme Silicate Absorbers in WISE

Proposal ID: OT2_jcolbert_2

Principal Investigator: James Colbert

Time: 12.7 hours priority 1

Category: High-z galaxies

Summary:

Using the WISE Preliminary Data Release mid-infrared and UKIDSS near-infrared catalogs, we have identified a sample of 0.8<z<1.5 infrared-bright galaxies with extremely large 9.7 micron silicate absorptions (~ 5 magnitudes). These highly obscured sources present a small but not well determined fraction of the whole ULIRG population, possibly representing one the earliest stages in the transition from star formation to black hole accretion domination, before the concealing gas and dust is expelled from the galaxy. From over 1200 square degrees and 1.6 million 12-micron sources, we extracted 230 extreme silicate absorbers, increasing the sample of known extreme silicate absorption sources by more than an order of magnitude from the mere handful (~5) now known. We propose to obtain 70, 100, and 160 micron PACS imaging of a sub-sample of 45 for which we have spectroscopic redshifts. This will allow us to measure and characterize the peak of the infrared emission providing total bolometric luminosities and allowing a full decomposition of the contributions of hot, warm, and cool dust within these extreme sources. We will also measure their mid-infrared continuum slope, critical for an accurate measurement of the depth of the silicate absorption feature. Combined with hot dust emission, the strength of the silicate absorption will put strong constraints on the size of emitting region.

### The Herschel Fornax Cluster Survey

Proposal ID: OT2_jdavie01_4

Principal Investigator: Jonathan Davies

Time: 31.1 hours priority 1

Category: Galaxy clusters/Lensing clusters

Summary:

We propose to use PACS and SPIRE in parallel mode to map about 45 sq deg of the nearby Fornax galaxy cluster. Our science objectives are mainly concerned with evolutionary processes within the cluster environment. Specifically we will derive FIR/sub-mm luminosity functions, construct complete spectral energy distributions, search for cold dust in the outskirts of galaxies and in the intra-galactic medium and consider and compared the properties early type and dwarf galaxies that are prolific within the cluster environment. The total time requested is 93.2 hours.

### A Herschel SPIRE study of star-formation in the host galaxies of the most luminous high-redshift quasars

Proposal ID: OT2_jdunlop_1

Principal Investigator: James Dunlop

Time: 58.3 hours priority 2

Category: High-z galaxies

Summary:

We propose to use this final Herschel call to obtain SPIRE 250,350,500 micron images of a sample of nearly 300 of the most luminous quasars to have ever existed in the universe. Our proposed programme samples the top decade of quasar optical luminosities, over the key redshift range 2.5 < z < 4.5, which corresponds essentially to the 1-2 Gyr epoch over which such objects are found. This regime has been neglected by current Herschel programmes, and our targets are too rare on the sky for more than a handful to be contained within the existing/planned Herschel SPIRE surveys. Via careful sample construction, including matched sub-samples of radio-loud and radio-quiet SDSS quasars, we aim to determine how dust-enshrouded star-formation activity in the host galaxies of these super-massive active black holes depends on their redshifts, and their optical/radio power. This will allow fundamental tests of the proposed linkage between galaxy and black-hole growth, and possible modes of feedback which seem to be required to shut down star formation in massive galaxies at these high redshifts. We believe it would be a major missed opportunity if Herschel is not used to assemble a legacy dataset for these, the presumed progenitors of today's most massive galaxies, especially since the data from this (relatively inexpensive) programme can ultimately be combined with comparable statistics on lower-luminosity quasars from the major SPIRE surveys such as H-ATLAS and HerMES (thus providing excellent coverage of the luminosity-redshift plane). Finally, since our quasar targets should mark some of the highest density regions in the young universe, we will explore the 12 sq arcmin sampled by Small-Map mode around each quasar to quantify the evidence for enhanced star-formation activity in the general vicinity of these quasar hosts, as anticipated if we are observing the progenitors of today's massive galaxy clusters.

### Identifying intense starbursts in a spectacular 3-way cluster merger at z~1

Proposal ID: OT2_jgeach_1

Principal Investigator: James Geach

Time: 8.2 hours priority 2

Category: Galaxy clusters/Lensing clusters

Summary:

We propose an experiment to investigate the evolution of the most massive galaxies that reside in the cores of massive clusters today. We aim to catch their progenitors - gas-rich, intensely starbursting galaxies - in the act of accretion onto massive halos at z~1. Our survey is unique because we will map a super-cluster environment that is in the throes of a spectacular 3-way merger, allowing us to examine the astrophysics of galaxy evolution during a key stage of the hierarchical build-up of large scale structure. Our target - RCS 2319 - is a system of three ~5x10^14 M_Sun galaxy clusters at z=0.9 separated by just 3 Mpc. RCS 2319 is the progenitor of a >10^15 M_Sun cluster, and the ideal target to examine the complex relationship between the formation of massive galaxies and the dense, dynamic environments they inhabit. We will obtain a deep map of RCS 2319 with SPIRE, covering a projected extent of 14x14 Mpc, including the full range of sub-environments from the dense cores out to the group-scale and filamentary structure in the super-cluster outskirts. Our goals are to (i) identify ULIRG-class (>10^12 L_Sun) cluster members and investigate their properties in the context of the super-cluster environment; and (ii) calculate the cross-power spectrum of FIR emission with galaxy surface density, allowing us to search for statistical correlations between obscured star formation and environment beyond the confusion limit.

### The highest redshift strongly lensed dusty star forming galaxies

Proposal ID: OT2_jvieira_5

Principal Investigator: Joaquin Vieira

Time: 16.5 hours priority 1

Category: High-z galaxies

Summary:

Large-area, multi-wavelength surveys from the ground and space have discovered a new population of strongly lensed, dusty, star-forming galaxies (DSFGs). These sources have lensing magnifications of x10-50 and present an exciting new means of studying otherwise faint high-redshift contributors to the cosmic infrared background (CIB) in exquisite detail. With its large survey area and long-wavelength selection, the South Pole Telescope (SPT) selects the rarest, brightest, and most interesting sample the sample of strongly lensed DSFGs and is enabling major advances in our understanding of massive galaxy formation.

Here we request 16.9 hours of SPIRE and PACS imaging to followup a sample of 88 sources from a 1.4 mm flux-limited sample with the aim of constraining SEDs to 1) estimate photometric redshifts, 2) measure dust temperatures, 3) derive the apparent and intrinsic IR luminosities, and 4) accurately determine molecular and atomic line to luminosity ratios. This proposal is part of a systematic followup campaign which includes approved and ongoing programs with HST, VLT, Spitzer, APEX, ATCA, and ALMA early science observations.

### SPIRE and PACS mapping of the A2125 field: the FIR properties of 1.2mm selected starburst galaxies

Proposal ID: OT2_jwagg_3

Principal Investigator: Jeff Wagg

Time: 7.2 hours priority 2

Category: High-z galaxies

Summary:

Little is known about the redshifted FIR properties of the 1.2mm selected sample of high-redshift, dusty starburst galaxies. Constraints on the dust temperature and total FIR luminosity depend on observations at short submm-wavelengths, which are only now possible with BLAST and Herschel. We have mapped a 0.5 square degree field at 1.2mm with MAMBO, centered on the Abell 2125 cluster. Complementary deep 1.4GHz radio imaging from the VLA has allowed us to identify radio counterparts to 83% of the 1.2mm selected galaxies, making this the largest sample of starburst galaxies selected at this wavelength with robust radio counterparts. We request 5.2 hours with PACS and 2.0 hours with SPIRE to map this field over the same area covered by MAMBO. These data will provide the first constraints on the (rest-frame) FIR spectral energy distribution of such a complete sample of 1.2mm selected starbursts.

### Revealing the ISM in high redshift galaxies: Herschel PACS observations of gravitationally lensed SMGs

Proposal ID: OT2_jwardlow_1

Principal Investigator: Julie Wardlow

Time: 78.9 hours priority 2

Category: High-z galaxies

Summary:

Little is currently known about the dominant mode of star-formation in high-redshift submillimeter-bright galaxies (SMGs), their relation to local ULIRGs and the contribution of AGN to their immense far-infrared (IR) luminosities. Observationally, the physical conditions in these sources are difficult to constrain because the most active regions are also the most highly obscured, and thus can only be probed with mid- and far-IR data. At high redshifts the PACS wavelength coverage is ideally suited to target critical fine structure emission lines from species including oxygen, nitrogen and silicon, and rotational transitions from molecular hydrogen. The relative fluxes of these emission lines, in combination with accurate far-IR luminosities, can be used to constrain the physical conditions in the ISM, such as the density and the ionization state, which in turn provides information about the star-formation triggers and AGN activity. However, most high-redshift galaxies are too faint for these emission lines to be detected, and therefore, studies of the high-redshift ISM are rare. We request Herschel PACS spectroscopy, and 70 and 160um photometry of 13 high-redshift (z~1 to 3), far-IR luminous, gravitationally lensed galaxies. These sources are unique -- the flux boosting from gravitational lensing means that it is feasible to observe them with Herschel, and they all have exceptional ancillary data which complements the proposed program and will maximise the science output from this project. Targets are selected from the H-ATLAS and HerMES surveys and comprise a complete sample of bright lensed SMGs with confirmed CO redshifts. The PACS photometry will constrain the far-IR SEDs, and identify any warm dust (i.e. AGN) components. The spectroscopy will be used to characterize the ISM in these sources, and will double the number of high-redshift galaxies for which such analysis is currently possible. We request a total of 78.9 hours for PACS spectroscopy (73.0 hours) and photometry (5.9 hours) of 13 sources.

### New light on dark Gamma-Ray Burst host galaxies with Herschel

Proposal ID: OT2_lhunt_3

Principal Investigator: Leslie Hunt

Time: 25.4 hours priority 1

Category: High-z galaxies

Summary:

Gamma-Ray Bursts (GRBs) are so luminous that they can shine through highly obscured galaxies, nearby and in the remote universe. GRBs enable identification of galaxies independently of their luminosity, thus singling out a population that is a potentially powerful probe of galaxy evolution. Here we propose PACS and SPIRE imaging of the host galaxies of dark GRBs, GRBs whose optical afterglow emission is weaker than expected relative to Xrays. Recent work suggests that the main cause of the optical darkness of a GRB is dust extinction and moderate redshift, and their hosts may be a significant component of the GRB host galaxy (GRBH) population at redshifts > 1. Our sample of 13 dark GRBHs has been carefully selected by requiring a prior Spitzer detection, so that we will be ensured of detecting the far-IR emission with Herschel. We already have collected a large amount of ancillary multiwavelength data which will be combined with the Herschel photometry to construct spectral energy distributions (SEDs) from the UV to the far-IR. Fitting SEDs with a library of galaxy templates will enable us to derive bolometric luminosities and SFRs, constrain dust mass, dust temperature, and grain properties, as well as stellar age and mass. We will compare the dust and stellar components of the galaxies, and analyze the GRBHs in the context of other high-z galaxy populations. Such a program is now possible thanks to the unique ability of Herschel to study dust emission in galaxies over a wide range of redshifts. Ultimately our proposed study of GRBHs will open a new window on the study of galaxy formation and evolution.

### The Physical Conditions of the Interstellar Medium in a Molecular Einstein Ring Submillimeter Galaxy at z~4

Proposal ID: OT2_maravena_2

Principal Investigator: Manuel Aravena

Time: 29.6 hours priority 1

Category: High-z galaxies

Summary:

Understanding the nature of the most distant starburst galaxies, in particular submillimeter galaxies (SMGs), has been one of the major challenges of modern observational cosmology. However, the intrinsic faintness, heavy obscuration and large cosmological distances of these systems have precluded the characterization of their optical properties and have limited their study to the rarest starburst galaxies. The most efficient way to investigate the properties of these systems is with the aid of gravitationally lensing at IR wavelengths. The recent discovery of a bright, highly magnified (m~12) SMG, MM18423+5939 at z~4, represents an unprecedented opportunity to understand in detail the interstellar medium (ISM) conditions in these objects and to bring such studies to a new level of detail. Follow-up observations with the EVLA showed that this source forms a spectacular molecular Einstein ring in CO high-resolution images, the second such object known to date. Here, we request 29.6 hrs of Herschel/SPIRE time to simultaneously observe, for the first time, three of the main coolants of the ISM: the O[I]63um, O[III]52um and O[III]88um emission lines, in a SMG at z~4. We will obtain a direct measurement of the physical state of the dense and warm gas phase that will be directly comparable to similar observations of local galaxies. We will combine these measurements with previous CO/[CI] observations of our target to provide a critical, detailed model of its ISM gas properties namely temperatures, H2 densities, e- densities and UV radiation field. Our on-going HST/WFC3 imaging program of our target is key, since it will allow us to accurately model the lens and source-plane gas distribution for a proper interpretation of the line emission. With a total IR luminosity of 1.3x10^14/m L_sun, this source has the potential to become the archetype for future deep spectroscopy with ALMA and dense gas studies at high-redshift.

### Completing the puzzle: Dense gas observations in star-forming disk galaxies at z~1.5

Proposal ID: OT2_maravena_3

Principal Investigator: Manuel Aravena

Time: 32.6 hours priority 1

Category: High-z galaxies

Summary:

The recent detection of large amounts of molecular gas in a sample of "normal" star−forming galaxies at z~1.5 has opened up a unique window into the study of the population of galaxies that dominates the star formation rate density of the Universe. Here, we propose pioneering PACS observations of the [OI]63um emission line in the best studied sample of four such galaxies that will allow us to carry out an unprecedented characterization of their star-forming properties. We aim to characterize the warm and dense neutral gas, in combination with our CO and FIR luminosity measurements, by comparing with radiative transfer models of the interstellar medium. We will be able to study the possible relation between the [OI] line and their main physical parameters (star formation rate, star formation efficiency, masses). Herschel is the only observatory capable of performing this kind of observations, that are forbidden to ground based observatories. We request a total of 32.63h of Herschel/PACS time toprovide the last piece in the puzzle that will permit to disentangle the properties on what appear to be the progenitors of galaxies like the Milky−Way.

### Herschel+CANDELS: Unraveling the physical processes that regulate star formation and AGN activity in ordinary galaxies at z=2

Proposal ID: OT2_mdickins_1

Principal Investigator: Mark Dickinson

Time: 193.6 hours priority 1

Category: High-z galaxies

Summary:

The deepest Herschel surveys have established a distinction between steady "main sequence" star formation, whose rate is closely tied to galaxy mass at a given redshift, and elevated starburst activity in ordinary, L*(IR) galaxies at z > 1.5. They have also shown that supermassive black hole growth occurs mainly through secular processes in these main sequence galaxies, and have revealed otherwise obscured AGN missed by the deepest X-ray surveys. However, the physical processes that trigger starbursts, and the relation between star formation, AGN activity, and the structural properties of galaxies at this peak era of galaxy growth, are far from clear. We propose a survey to address these questions by measuring far-infrared luminosities and star formation rates for a large sample of high redshift galaxies with deep, high-resolution near-infrared imaging from the CANDELS HST WFC3 Treasury program. Herschel PACS and SPIRE observations deep enough to detect 700+ L*(IR) galaxies at z > 1.5 will be obtained for the five CANDELS fields and correlated with the detailed morphological and structural properties that only HST/WFC3 imaging can provide. We will establish whether interactions and mergers drive starburst activity, and examine their relevance for fueling AGN activity. The improved statistics will allow a definitive measure of the space density of L*(IR) galaxies at z=2, a basic (and currently very uncertain) demographic quantity for the history of cosmic star formation. The survey will provide a legacy of targets for detailed investigation with ALMA, tripling (beyond GOODS-South alone) the number of ALMA-accessible fields with the deepest Herschel data.

### A Search for Star Formation and Cool Gas in the Anomalous Cluster Abell 2029

Proposal ID: OT2_mmcdonal_1

Principal Investigator: Michael McDonald

Time: 6.8 hours priority 2

Category: Galaxy clusters/Lensing clusters

Summary:

We propose to obtain deep IR imaging at 70um, 100um, and 160um with PACS (3.4h), and PACS spectroscopy of the [C II] 158um line (3.4h) for the anomalous galaxy cluster Abell 2029. This cluster has similar properties to both cool core (low central entropy, UV emission, radio-loud) and non-cool core (no measurable cooling in X-ray, no detectable H-alpha or CO) clusters, suggesting that it may be a transition object. The presence of young stars, inferred by extended UV emission, coupled with the absence of H-alpha emission, is evidence for a recent (~10 Myr) starburst. The missing piece to this puzzle is the mid-far IR, which is the only wavelength range that has not been well studied in this system. The addition of deep mid-far IR photometry will allow us to i) confirm/disprove the presence of a young stellar population, and ii) infer a starburst age based on the dust temperature. Deep IR spectroscopy of the [C II] will probe for a hidden reservoir of cool gas and would provide an estimate of the cooling rate at lower temperatures. Combined, these observations will shed new light on a galaxy cluster that, despite its proximity and the availability of deep, multi-wavelength data, has long defied understanding.

### Herschel Spectroscopy of Lensed High-Redshift Galaxies.

Proposal ID: OT2_mrex_2

Principal Investigator: Marie Rex

Time: 6.6 hours priority 2

Category: High-z galaxies

Summary:

We propose Herschel spectroscopic observations of the [C II]158 um and [O I]63 um emission lines in 4 extremely bright, lensed, high-redshift galaxies. Herschel photometric surveys conducted toward galaxy clusters have identified these highly magnified sources, which would otherwise be undetectable below the confusion limit of the instrument. These exceptional targets provide the unique opportunity to study the characteristics of the ISM in typical galaxies with moderate luminosities at high redshift.

Recent studies have identified key differences between the far-infrared properties of local LIRGS/ULIRGS and galaxies of comparable luminosity at high redshift. However, the highest redshift observations are inherently biased toward more luminous galaxies, making it difficult to extend this comparison to the abundant population which is intrinsically faint. Herschel spectroscopy of highly magnified galaxies provides the only means to probe the physical conditions within this more typical population. Measurements of the [C II] and [O I] cooling lines are sensitive to the temperature and density of the gas surrounding star−forming regions, as well as the strength of the incident far ultraviolet radiation from starbursts. These observations will provide insight into the environmental conditions that drive the differences between high-redshift star-forming galaxies and those in the local universe.

### The Herschel Redshift Survey (HeRS)

Proposal ID: OT2_mviero_2

Principal Investigator: Marco Viero

Time: 34.7 hours priority 1

Category: Cosmology/Extra-galactic surveys

Summary:

A substantial fraction of the star-formation history of the Universe is encoded in the cosmic infrared background (CIB), but fundamental issues about the sources which make up the CIB such as their redshift distribution, their stellar masses, and the masses of their host halos remain poorly constrained by current measurements.  To address these issues, we propose the Herschel Redshift Survey (HeRS), a 70 deg2 SPIRE survey in the SDSS Stripe 82.  HeRS is designed to leverage the unprecedented spectroscopic redshift and stellar mass catalogs of the Hobby Eberly Telescope Dark Energy Experiment (HETDEX) and Spitzer-HETDEX Exploratory Large Area (SHELA) Survey, in order to provide the most precise constraints yet obtained on the obscured star-formation properties of galaxies in the redshift range 1.8 < z < 3.5. HeRS will principally target two goals: i) the redshift distribution of the infrared light that makes up the cosmic infrared background; and ii) the evolution of the specific star-formation rate of galaxies as a function of redshift.  Our measurements will far outstrip any that could be made with existing or planned SPIRE surveys because the high level of confusion noise (3–30 times higher than the signal) requires cross-correlating maps with the highest quality ancillary data: specifically, data that provides extremely accurate redshifts and reliable stellar mass estimates over a wide area.  And only HETDEX spectroscopic redshifts are capable of measuring the density field and bias to the required 1–2% accuracy. These measurements will break the luminosity/redshift degeneracy plaguing the interpretation of correlation studies of the CIB, and place tight constraints on source population models. This observing cycle represents the last chance to obtain Herschel observations of what will be one of the premier cosmological fields for years to come.

### Complete Spectral Mapping of the Sub-Millimetre Sunyaev-Zelâdovich Effect in Galaxy Clusters.

Proposal ID: OT2_mzemcov_1

Principal Investigator: Michael Zemcov

Time: 13.7 hours priority 1

Category: Galaxy clusters/Lensing clusters

Summary:

We propose to measure relativistic corrections to the Sunyaev-Zel'dovich effect (rSZ) in two clusters of galaxies with SPIRE-FTS, providing measurements of the intra-cluster medium (ICM) temperature with ~30 arcsec spatial resolution. For the first time, these measurements will enable: 1) unambiguous, high significance measurement of the rSZ correction, and 2) precise determination of the temperature substructure of extremely hot clusters. Both measurements are technically feasible with SPIRE-FTS and are inaccessible in any other way. The value our proposed observations for demonstrating the ability to measure the temperature of ICM substructures in massive, complex clusters is enormous, both for cosmological applications (i.e. a precise and unbiased determination of the total mass of clusters) and for astrophysical applications (untangling the complex atmosphere of clusters using SZ). These measurements will prove that measurements of the rSZ correction can enable important new studies of cluster physics and the fleeting opportunity to make them should not be missed.

### Understanding Obscured Star Formation Active Galactic Nuclie and Dust Formation at z~5

Proposal ID: OT2_pcapak_2

Principal Investigator: Peter Capak

Time: 37.1 hours priority 2

Category: High-z galaxies

Summary:

We propose PACS photometry to constrain the rest frame infrared (15-40um) properties of six 4.5<z<5.3 spectroscopically confirmed extreme starbursts (sub-mm) galaxies, tripling the sample size of well studied galaxies at z>4. This will allow us to: 1) Obtain accurate total infrared luminosity measurements for these sources resulting in an unbiased measure of star formation at z~5; 2) Determine the relative contribution of Active Galactic Nuclie (AGN) and star formation to the total infrared luminosity; 3) Characterize the amount of warm dust emission in these galaxies and compare it to their gas properties; 4) Create templates for "typical" z~5 extreme starburst (sub-mm) galaxies to inform theoretical exploration and enable photometric searches for larger samples of objects. The existing 110um and 160um PACS survey data are not deep enough to fully constrain the infrared spectral energy distributions are crucial to confirm the nature of these systems and provide tight constraints on models for dust formation in the early universe.

### Shocked molecular and atomic gas in the Spiderweb radio galaxy at z=2.156

Proposal ID: OT2_pogle01_2

Principal Investigator: Patrick Ogle

Time: 14.8 hours priority 1

Category: High-z galaxies

Summary:

PACS spectroscopy of the Spiderweb radio galaxy (PKS 1138-26) at redshift z=2.156 will be used to study jet-shocked molecular and atomic gas in a rapidly evolving protocluster central galaxy. This will lead to a better understanding of the impact of AGN feedback on the evolution of massive elliptical galaxies in general. We have detected extremely luminous (7E10 Lsun) H2 0-0 S(3) emission in a deep Spitzer IRS spectroscopic map. This is by far (a factor of 50) the most luminous known molecular hydrogen emission galaxy. We estimate that there must be >1E7 Msun of warm (T=650 K) molecular gas heated by dissipation of kinetic energy from the relativistic radio jet. PACS spectroscopy of the H2 0-0 S(0) line will enable us to measure the mass of warm H2 at lower temperature (T=100-500) K, which likely constitutes the bulk of the shocked molecular gas, possibly >1E11 solar masses. We have also detected ultraluminous PAH emission indicating a star formation rate of 1000 Msun/yr. PACS spectroscopy of the [Si II] 35 micron and [O I] 63 micron cooling lines will provide additional diagnostics of the shocked neutral medium, including distinguishing between magnetic and nonmagnetic shocks, and assessing the kinematics of this important ISM component in a massive elliptical galaxy under construction.

### Linking and Understanding Extinction and Emission by Dust in Evolved GRB Host Galaxies

Time: 6.2 hours priority 1

Category: High-z galaxies

Summary:

We propose observations in the two reddest PACS and all three SPIRE bands of the host galaxies of a sample of five GRBs. The sample was carefully selected based on the detection of large extinction in the GROND SED of the GRB afterglow, and all hosts have a large amount of multiwavelength data in hand, including sensitive submm observations. Together with the Herschel data, we will model the SEDs from the UV to the submm with the broadband galaxy SED fitting software, CIGALE, to derive bolometric luminosities and SFRs, and constrain dust mass and dust temperature. We will compare the dust properties of the whole galaxy with that derived from the GRB afterglow to constrain the dust clumpiness (covering fraction, total extinction). We will also compare the dust and stellar components of the galaxies, and investigate the GRB hosts in the context of other high-z galaxies. The Herschel data will provide indispensable observations of the peak of the thermal dust emission component, which accompanied with our APEX and SCUBA submm observations will provide the most accurate measurements to date of the extinction and emission properties of dust within GRB host galaxies.

### Starbursting and quenching around a massive galaxy cluster at z~0.5.

Proposal ID: OT2_rcybulsk_4

Principal Investigator: Ryan Cybulski

Time: 27.9 hours priority 2

Category: Galaxy clusters/Lensing clusters

Summary:

We propose Herschel PACS mapping of the central 64 square Mpc around the massive galaxy cluster MS0451 (at z=0.54) to determine the dominant physical mechanisms that trigger and quench star formation in galaxies over a wide dynamic range of local environments. MS0451 is one of the most massive, X-ray luminous clusters known, and previous studies of galaxies within the virial radius of MS0451 have found strong evidence for abrupt quenching of star formation, likely due to ram-pressure stripping by the hot intra-cluster medium (Geach et al. 2006, Moran et al. 2007). Studies focusing only on the cluster core are not sensitive to transformative effects that can begin to alter the morphology, color, and star formation rate (SFR) of galaxies on the cluster outskirts. Our observations will allow for robust measurements of star formation rates as low as ~30Msun/yr for galaxies out to ~2Rvir, and will give a more complete picture of the effect of environment on the evolution of galaxies via triggering and quenching of their star formation.

### The formation and evolution of proto-clusters

Proposal ID: OT2_rhuub_2

Principal Investigator: Rottgering Huub

Time: 21.6 hours priority 1

Category: Galaxy clusters/Lensing clusters

Summary:

Understanding how massive black holes, galaxies and clusters of galaxies jointly emerged from inhomogeneities in the primeval Universe is one of the most compelling objectives of modern observational astrophysics. Here we propose to use SPIRE's excellent sensitivity and survey speed to obtain for the first time a significant sample of proto-clusters over the key redshift range 2 < z < 4. This would be done through imaging of fields centered at AGN selected to harbour the most massive black hole. The resulting data set will allow us to address key questions, including: (i) Are the most massive black holes at z > 2 located in the largest and most massive proto-clusters? (ii) What are the masses, sizes, total star formation rates and velocity dispersions of the protoclusters? (iii) What are the masses, ages and star formation rates of the individual proto-cluster galaxies? Do we see a spatial segregation of galaxies with different masses or star formation rates? (iv) Do the properties of the proto-clusters and their galaxies evolve with redshift? (v) Are the galaxies in these proto-clusters older, larger and more massive then field galaxies?

### Herschel-GAMA: Gas-fuelling Feedback and Star-Formation in Galaxy Groups in the Local Volume

Proposal ID: OT2_rtuffs_2

Principal Investigator: Richard Tuffs

Time: 25 hours priority 1

Category: Galaxy clusters/Lensing clusters

Summary:

Herschel-GAMA: Gas-fuelling, Feedback and Star-Formation in Galaxy Groups in the Local Volume

Under the Cold Dark Matter paradigm the propensity of intergalactic baryons to cool and accrete onto existing galaxies or form new galaxies depends both on the mass of the inhabited dark matter halo through the process of virialisation, as well as on the mass, dynamical state and gas content of individual galaxies, since the latter can either enhance or hinder accretion though so-called feedback from starformation or AGN activity. We have used the unprecedented density of redshifts furnished by the Galaxy And Mass Assembly (GAMA) deep wide field spectroscopic survey to identify the first statistically significant sample of low mass groups, opening the way for deep pointed multiwavelength investigations to probe baryonic processes over a more representative population of haloes than previously possible. Here we propose deep pointed miniscan exposures with PACS at 70, 110 and 160 microns of a representative subsample of 57 low-mass blue sequence member galaxies of GAMA groups with z less than 0.04 spanning a range in dynamical mass between 10^11 and 7.10^13 M_solar and a range in galaxian stellar masses from 10^8.0 to 10^9.25, parameter space that has not yet been surveyed in the FIR. Combining this with corresponding multiwavelength data on existing blind surveys covering the GAMA footprint and deep surveys of massive clusters, we will provide a complete picture of the UV-FIR/submm emission from blue sequence galaxies spanning four orders of magnitude in host halo mass and three orders of magnitude in stellar mass. This will provide a comprehensive picture of the variation of present day SF activity with environment which will serve as a fundamental empirical constraint on the baryonic processes determining the relation of our visual perception of the Universe to its underlying DM structure.

### Measuring [OI]63um and [OIII]88um in a sample of SPIRE-selected galaxies at z=1-2

Proposal ID: OT2_schapman_10

Principal Investigator: scott chapman

Time: 24.9 hours priority 2

Category: High-z galaxies

Summary:

We propose to use PACS to observe the forbidden fine-structure line [OI]63μm, and for six of the sources, the [OIII]88μm line, in a sample of 16 Herschel-SPIRE selected ULIRGs, spectroscopically confirmed at z = 1−2 (keeping [OI] in the PACS-spectrometer band). We have further chosen the sources to lie in a single southern field in order to exploit the synergy with ALMA, to provide additional line diagnostics, and to emphasize the advantage of gaining insight into an unlensed galaxy population, both from environmental effects, and to avoid the differential lensing bias which can plague line ratio diagnostics. This represents a unique sample of objects made possible only with the advent of SPIRE ULIRG selection at high−z, and importantly filling a void in existing or planned similar observations with PACS; an allocated program in OT1 (in the same field) focussed on a small sample of 870μm selected SMGs, lying mostly at z = 1.0–1.3 with a few AGN-dominated systems at z = 1.3–2.0. Our targets (which don’t overlap) will complement this sample of sources in the same cosmic volume.

### Herschel Extreme Lensing Line Observations (HELLO)

Proposal ID: OT2_smalhotr_3

Principal Investigator: Sangeeta Malhotra

Time: 59.8 hours priority 1

Category: High-z galaxies

Summary:

We request 59.8 hours of Herschel time to observe 20 normal star-forming galaxies in the [CII] 158 micron and [OI] 63 micron lines. These galaxies lie at high redshift (1<z<3). They are highly magnified by gravitational lensing, but have modest star formation rates. Therefore they represent our best chance of studying star formation and the interstellar medium in typical, common galaxies at this epoch. Redshift 1 to 3 spans the peak of both star formation activity and black hole accretion in active galactic nuclei-- a period that was crucial in shaping our modern universe. Most of this redshift range is inaccesible to ground-based observations of [CII], [OI], or both. Herschel offers the unique opportunity to study both lines with high sensitivity throughout this epoch (using HIFI for [CII] and PACS for [OI]). These two lines are the main cooling lines of the atomic medium. By measuring their fluxes, we will measure (1) the cooling efficiency of gas, (2) gas densities and temperatures near star−forming regions, and (3) gas pressures, which are important to drive the winds that provide feedback to star−formation processes. By combining the proposed observations with existing multiwavelength data on these objects, we will obtain as complete a picture of galaxy-scale star formation and ISM physical conditions at high redshifts as we have at z=0. Then perhaps we can understand why star formation and AGN activity peaked at this epoch. In Herschel cycle OT1, 49 high redshift IR luminous galaxies were approved for spectroscopy, but only two so-called normal galaxies were included. This is an imbalance that should be corrected, to balance Herschel's legacy.

### Exploring dust-obscured star formation in the bullet-like cluster A2163

Proposal ID: OT2_smaurogo_2

Principal Investigator: Sophie Maurogordato

Time: 14 hours priority 2

Category: Galaxy clusters/Lensing clusters

Summary:

We propose to address the impact of a major merging event on star formation on the bullet-like cluster: Abell 2163. This very massive cluster, among the most luminous and hottest clusters observed in X-Ray, shows outstanding properties from X-ray to radio wavelengths. Thanks to an extensived combined Xray/optical/weak-lensing program, we have recently reconstructed the merging history of this cluster (Maurogordato et al. 2008, Bourdin et al. 2011, Okabe et al. 2011) showing definitively the occurence of a recent major merger (< 0.5 Gyr) with a fast moving gas core spatially segregated from galaxies and dark matter. Suggesting an efficient stripping of the gas core by ram pressure (Okabe et al. 2011) such a clear spatial segregation has been detected so far in very few massive clusters, the most spectacular one being 1E 0657-56, the so-called"bullet cluster". A2163, at z=0.2, is the nearest one, making it an excellent target to address in details the effect of ram pressure induced by a major merger event. Besides the "bullet" in the central region, Abell 2163 shows a filamentary complex, embedding several groups and a sub-cluster being accreted along the filament, making it also a very interesting environment to address the efficiency of galaxy pre-processing in groups and filamentary structures. We propose to perform observations of A2163 with Herschel using PACS (100 and 160 microns: 12.7h) and SPIRE (250, 350 and 500 microns: 1.3 h), requesting a total time of 14.0h. Together with extensive ancillary data on this cluster, these observations will allow us to perform good estimates of star formation rates, and recover the stellar masses and star formation histories of cluster galaxies. These will be used to test the impact of the cluster merger event and its large scale environment on star formation.

### Testing the Gamma Ray Burst standard model through Herschel observations of their host galaxies.

Proposal ID: OT2_soates_1

Principal Investigator: Samantha Oates

Time: 25 hours priority 2

Category: High-z galaxies

Summary:

Long gamma-ray bursts (LGRBs), are the brightest transient events in the Universe. This, combined with their wide range in redshift and the fact that they are associated with the collapse of massive, low metallicity stars, establishes LGRBs as powerful probes of star formation and an unbiased method for identifying high redshift galaxies. However, due to biases in the detection of the optical emission associated with LGRBs and lack of host measurements at infrared wavelengths, it is currently unclear whether we have a representative picture of the LGRB host galaxy population. In particular, there is tentative evidence to suggest that a significant fraction of LGRB hosts are dusty and hence luminous in the infrared, an issue which can be settled uniquely with Herschel. Here we propose the first statistical study of LGRB host galaxies with Herschel/SPIRE, requesting 25 hrs of observations. Our sample of 100 LGRB host galaxies have a redshift distribution which peaks at z=2.0 and are split 50:50 into dark and bright, these classifications referring to the strength of the optical afterglow emission following the LGRB. Although, we expect a significant fraction (>20%) of the sample to be individually detected in SPIRE enabling more detailed examination of these sources, we plan to obtain a representative view of the dust properties of LGRB hosts by stacking the SPIRE images of the bright and dark sub-samples. The SPIRE bands will probe the peak of the dust emission over most of the redshift range covered by our sample, enabling us to determing average and representative measurements of the dust content, infrared luminosity, star-formation rate, dust mass/temperature and extinction for LGRB hosts. Our proposed observations are the only opportunity to compare the global dust properties of bright and dark LGRB hosts, with the results from our study having important implications in LGRB theory and LGRB progenitor models.

### THE HERSCHEL-AKARI NEP DEEP SURVEY: the cosmological history of stellar mass assembly and black hole accretion

Proposal ID: OT2_sserje01_2

Principal Investigator: Stephen Serjeant

Time: 6.2 hours priority 1

Category: High-z galaxies

Summary:

We propose a far-IR and submm mapping survey of the premier AKARI deep field in the North Ecliptic Pole, in PACS/SPIRE parallel mode. This is the only major deep infrared field not yet covered by Herschel guaranteed or open time key projects. The outstanding and unparalleled continuous mid-IR photometric coverage from AKARI, far better than equivalent Spitzer surveys, enables a wide range of galaxy evolution diagnostics unachievable in any other survey field (including Herschel HerMES/PEP fields), by spanning the wavelengths of redshifted PAH and silicate features and the peak energy output of AGN dust tori. The investment by AKARI in the NEP represents ~10 percent of the entire pointed observations available throughout the lifetime of AKARI. Our proposal remedies the remarkable omission from Herschel's legacy surveys of the premier extragalactic deep field from another IR space telescope.

We will simultaneously identify and find photometric redshifts for the Herschel point source population, make stacking analysis detections of the galaxies which dominate the submm extragalactic background light as a function of redshift, determine the bolometric power outputs of the galaxies that dominate the submm background, compare the UV/optical/mid-IR continuum/PAH/far-IR/submm/radio star formation rate estimator in the most comprehensive IR survey data set to date, and track the coupled stellar mass assembly and black hole accretion throughout most of the history of the Universe.

In OT1 the HOTAC concluded "The science output from the proposed survey will be outstanding [...] The panel was convinced that these observations should be done" but it since became clear that priority 2 time is very unlikely to be executed, so we request reclassification to priority 1.

### Dust in the wind: the role of dust in ram-pressure stripped gas and intracluster star formation (Part II)

Proposal ID: OT2_ssivanan_2

Principal Investigator: Suresh Sivanandam

Time: 12.5 hours priority 1

Category: Galaxy clusters/Lensing clusters

Summary:

We propose to detect dust associated with ram−pressure stripping through deep Herschel PACS/SPIRE imaging of a carefully chosen set of cluster galaxies that show strong signs of on−going stripping and intracluster star formation. This is a continuation of our OT1 program where we have successfully detected a dust tail caused by ram-pressure stripping in the one case where we have obtained a complete PACS/SPIRE photometer dataset. Our highest priority OT1 targets have not been observed, and our original sample was small, consisting of only five galaxies. Based on our current success, we have further refined our selection criteria to only choose galaxies within the high pressure cluster environment that show signs of intracluster star formation primarily due to ram-pressure stripping of gas. Our program will carry out deep Herschel observations of six galaxies that have highly extended (~20−80 kpc) UV and H_alpha tails associated with intracluster star formation. Herschel is the only telescope that has the sensitivity to detect the emission from dust blown out into the intracluster medium (ICM). With our proposed observations we aim to: 1. quantify the temperature, mass, and lifetime of dust blown out into (or formed in-situ within) the ICM; 2. understand the role dust plays in the existence of molecular hydrogen in the ICM and intracluster star formation. The Herschel observations will expand our already large multi−wavelength dataset and finally provide complete inventory of the gas and dust associated with ram−pressure stripping, so we can study the effects of ram−pressure on galaxy evolution. This will be the last opportunity in a very long time to make these measurements.

### Probing the Physical Conditions of the Interstellar Medium in High Redshift Radio Galaxies

Proposal ID: OT2_tgreve_1

Principal Investigator: Thomas Greve

Time: 13.1 hours priority 2

Category: High-z galaxies

Summary:

High redshift radio galaxies (HzRGs) are the most dramatic examples of the formation of massive galaxies in the early Universe, as evidenced by their extreme (>1000Msun/yr) star formation rates. At the same time they coincide with a phase of rapid coeval black hole (BH) growth, as revealed by their powerful active galactic nuclei (AGN). This makes HzRGs unique laboratories in which to study the coevolution of massive galaxies and their central BHs. Our team has successfully carried out comprehensive imaging surveys of 62 powerful HzRGs at z > 1 using Spitzer and Herschel. These surveys have demonstrated that HzRGs have high stellar masses (>1e11Msun), and mid-IR AGN luminosities comparable to the most powerful QSOs known. Also, they have allowed us to separate the AGN and starburst contributions to the total IR luminosity. In parallel to this, we are undertaking a large CO(1-0) line survey towards a subset of 10 HzRGs using ATCA, which will provide us with excitation-unbiased mass estimates of the total molecular gas available for star formation. With this proposal we will constrain the bulk physical conditions of the star forming gas in HzRGs using the far-infrared OI fine-structure line at 63micron, which is one of the brightest diagnostic lines of the interstellar medium (ISM) in galaxies. The [OI] line, which can contain as much as >0.1% of the total IR luminosity of a galaxy, is one of the major coolants of the ISM, and is expected to be particular bright in the type of dense, hot, star forming gas expected to dominate the ISM in HzRGs. Utilizing our accurate IR luminosity estimates and molecular gas masses in combination with [OI] we will employ photo-dissociation models to constrain the gas density and the impinging FUV radiation field. We request a total of 13.1hrs of PACS spectroscopy (~2.2hrs per source, ensuring a S/N > 5) in order to detect the [OI] line towards six carefully chosen HzRG, representative of the luminous 1 < z < 2.3 radio galaxy population.

### 70um photometry to constrain unusually warm dust in cluster galaxies

Proposal ID: OT2_trawle_3

Principal Investigator: Tim Rawle

Time: 26.1 hours priority 2

Category: Galaxy clusters/Lensing clusters

Summary:

Complete 6 band (70-500um) observations of spectroscopically-confirmed cluster members in the Bullet Cluster have revealed a galaxy population with unexpectedly warm dust (T>40K) for sub-LIRG sources. No field sources of similar luminosity, at any redshift, have comparable dust temperatures, indicating that such warm dust may at least be preferentially located in dense environments. There are currently two problems testing this hypothesis more rigorously: (1) constraining the temperature of warm dust at z~0.3, requires 70um data, as the peak moves blue-ward of the range adequately constrained by 100 and 160um alone; (2) 70um observations of massive clusters are rare, as Spitzer/MIPS was only sensitive enough to probe the nearest poor cluster environments, and Herschel programs have tended to opt for only the 100um filter configuration. Indeed, the Bullet Cluster remains one of the only massive clusters with deep 6-band Herschel photometry.

Here we propose deep 70um PACS observations of four clusters from the Herschel Lensing Survey (HLS): A68, A2744, AS1063, A851 (26.1 hours in total). This sample has the advantage of existing deep 5-band Herschel data, as well 5-band Spitzer IRAC/MIPS coverage and a wealth of optical ancillary data, including 1000s of spectroscopic redshifts. The systems cover a range of cluster morphologies (multi-component mergers to relaxed systems). The observations will allow us to: (1) constrain the characteristic dust temperature of cluster galaxies with unusually warm dust; (2) search for similarly warm dust in foreground field galaxies to assess whether the phenomenon is a product of environment; (3) better constrain the FIR luminosity for all Herschel sources, using 70um to sample the mid-IR gap between 24 and 100um, and the deeper 160um data to increase the number of SPIRE sources detected by PACS; (4) improve Herschel-based photometric redshifts for high-z lensed sources.

### PACS photometry for Spire Snapshot Survey bright high-Z sources

Proposal ID: OT2_trawle_4

Principal Investigator: Tim Rawle

Time: 7.2 hours priority 2

Category: High-z galaxies

Summary:

Gravitational lensing offers a powerful method of observing intrinsically faint, high-redshift sources. Until recently, only a handful of FIR-bright, lensed galaxies have been discovered. Most of these are magnified by a single foreground galaxy, which can be difficult to disentangle spatially. Cluster lensing, on the other hand, offers the ability to accurately reconstruct the morphology of the magnified source. The SPIRE Snapshot Survey (currently 78 clusters observed from a sample of ~280) has so far discovered 10 bright, high redshift (z>1.5) sources. These include a confirmed z=4.69 source with 4 identified optical images coincident with submm peaks, and a z=2.4 source with a 500um flux of 230 mJy. We propose PACS 100 and 160 um observations for the 10 sources (total observing time of 7.2 hours), to complete the FIR SED and enable us to accurately constrain the FIR luminosity and dust properties.

### Witnessing the assembly of a massive cluster at z = 1: a microcosm for the SFR-density relation of the universe

Proposal ID: OT2_twebb_3

Principal Investigator: Tracy Webb

Time: 58.8 hours priority 2

Category: Galaxy clusters/Lensing clusters

Summary:

We request deep PACS imaging observations of a rare merging super-cluster, RCS2319, at z = 0.9. This system is projected to form a 10^15 MSun cluster by z = 0.2, but has been caught in the process of its assembly through the merging of three massive clusters. At this redshift star formation has migrated to higher density regions than seen locally, but it is not clear if the peak of the star-formation-rate-density relation has yet reached cluster core densities. This systems can directly answer this question by probing a wide range of galaxy environments and densities within a single uniform data set. We have assembled an extensive catalog of spectroscopy and imaging which allows us to trace the galaxy density and substructure within RCS2319 and control for galaxy mass, but lack the infrared measurements necessary for accurate star formation rates that Herschel alone can provide. With these measurements we will characterize the role of the environment in stellar mass assembly, investigate the hierarchical processes of merging and infall through which massive clusters form, and elucidate the cluster-specific mechanisms which regulate galaxy evolution within dense environments.

### The Herschel Proto-cluster Survey: SPIRE Mapping of the Nodes of the Cosmic Web at z>2

Proposal ID: OT2_ymatsuda_1

Principal Investigator: Yuichi Matsuda

Time: 11.9 hours priority 1

Category: High-z galaxies

Summary:

We propose an experiment to search for signatures of rapid growth of galaxies and AGNs in a sample of three z>2 proto-clusters. These environments are exceptionally rare, pre-virialised regions corresponding to peaks in the matter density field, located at the nodes of large-scale (>10-Mpc) filamentary structures. They are the best candidates for the progenitors of the most massive clusters of galaxies (~10^15-Msun) today. We pay special attention to an unusual class of object, preferentially located in proto-clusters: Lyman alpha blobs (LABs) - 100-kpc scale luminous emission-line gas nebulae. Some LABs show signatures of recent galaxy-galaxy mergers/interactions, are often host to luminous continuum sources, and many have evidence of gas inflows/outflows in their emission-line morphology. A significant fraction of LABs have embedded galaxies detected at X-ray, mid-infrared, and/or sub-mm wavelengths, suggesting possible rapid growths of the galaxies and AGNs in proto-cluster regions. Are the proto-cluster systems more obscured than galaxies in the field? Are the protocluster systems growing more rapidly? By mapping these proto-clusters with SPIRE, we will: (1) measure SFRs in sub-mm (rest-frame FIR) for the galaxies and AGNs in the proto-clusters, and determine how much star formation is obscured (when compared to UV estimate) and (2) determine SSFRs for the galaxies and AGNs in the proto-clusters, and see how they compare to field galaxies at z=2-3. This program will deliver fundamental information on the growth of galaxies and super-massive black holes in the densest regions of the Universe at high-redshift, and provide valuable insight into the astrophysical processes that establish the trends linking galaxy properties and their environments.