Massive Galaxies Over Cosmic Time 3 - National … Galaxies Over Cosmic Time 3 The Role of Gas and Dust National Optical Astronomy Observatory Association of Universities for Research

Massive Galaxies Over Cosmic Time 3

The Role of Gas and Dust

National Optical Astronomy Observatory Association of Universities for Research in Astronomy

NASA Herschel Science Center Spitzer Science Center Steward Observatory

November 8 - 10, 2010 –Tucson, Arizona

Scientific Organizing Committee Romeel Davé (U. of Arizona) Arjun Dey (NOAO)

Vandana Desai, co-chair (SSC) David Elbaz (CEA Saclay)

Dave Frayer (NRAO) Jason Melbourne (Caltech)

Alexandra Pope, co-chair (UMass) Linda Tacconi (MPE)

Local Organizing Committee Stéphanie Juneau (U. of Arizona) Jeyhan Kartaltepe, chair (NOAO) Desika Narayanan (U. of Arizona)

Kyle Penner (U. of Arizona) Shelley Weintraub (NOAO)

Talk Schedule

Monday, November 8 8:00 – 9:00 Breakfast Session I: Accretion processes in massive galaxy formation (Chair: Arjun Dey) 9:00 – 10:00 Dusan Keres* - Gas Accretion in Galaxies

9:30 – 10:00 Jennifer Lotz* - Galaxy Mergers Through Cosmic Time

10:00 – 10:30 Avishai Dekel* - Feeding Massive Galaxies in their Most Active Phase of Assembly and Star Formation 10:30 – 10:50 Coffee Break 10:50 – 11:05 Greg Rudnick - The Efficiency of Clusters at Stopping Gas Accretion in Galaxies

11:05 – 11:20 Mauro Giavalisco - Discovery of Massive Amounts of Cold HI Gas in a Galaxy Overdensity at Redshift z~1.6

11:20 – 12:30 Discussion led by Frédéric Bournaud 12:30 – 2:00 Lunch Session II: Star formation in massive galaxies (Chair: Vandana Desai) 2:00 – 2:30 Guinevere Kauffmann* - What can be Learned from the Atomic and

Molecular Gas Scaling Relations of Nearby Galaxies?

2:30 – 3:00 Casey Papovich* - On the Star Formation Rates and Star Formation Histories of Massive Galaxies

3:00 – 3:30 Emanuele Daddi* - Star Formation Modes in Distant Massive Galaxies 3:00 – 3:50 Coffee Break 3:50 – 4:05 Chris Hayward - The Contribution of Merger-Induced Starbursts to the

Sub-Millimeter Galaxy Population

4:05 – 4:20 Carrie Bridge - WISE-selected Lyman-alpha Blobs at z~2

4:20 – 5:20 discussion led by Rachel Somerville 6:00 – 8:00 Cocktails & Hors D'oeuvres * Invited Speaker

Tuesday, November 9 8:00 – 9:00 Breakfast Session III: Role of AGN during active, high SFR phase (Chair: Jason Melbourne) 9:00 – 9:30 Phil Hopkins* - How do Massive Black Holes Get their Gas

(and Get Rid of It)?

9:30 – 10:00 Eliot Quataert* - Feedback From Radiation Pressure During theGrowth of Massive Galaxies and Their Central Black Holes

10:00 – 10:30 Dieter Lutz* - A Herschel View on Star Formation in High Redshift AGN Hosts

10:30 – 10:50 Coffee Break 10:50 – 11:05 Stéphanie Juneau - Linking Starbursts, Major Mergers, and Absorbed

AGNs at Redshift~0.7

11:05 – 11:20 Jerry Ostriker - The Two Phase Evolution of Massive Galaxies

11:20 – 12:30 Discussion led by Tim Heckman 12:30 – 2:00 Lunch Session IV: Internal structure of galaxies during high SFR phase (Chair: David Frayer) 2:00 – 2:30 Reinhard Genzel* - Gas-rich Massive Disks at z~2

2:30 – 3:00 Leo Blitz* - The Gas Consumption History Over Cosmic Times

3:00 – 3:30 Thorsten Naab* - A Theoretical View on the Internal Structure of High Redshift Galaxies

3:00 – 3:50 Coffee Break 3:50 – 4:05 Andrew Baker - Cold Gas Inventories in Massive High-redshift

Galaxies

4:05 – 4:20 Linda Tacconi - High Gas Fractions and the K-S Relation for "Normal" Star Forming Galaxies From z=1-3

4:20 – 5:20 Discussion led by Nick Scoville 6:00 – 8:00 Cocktails & Hors D'oeuvres * Invited Speaker

Wednesday, November 10 8:00 – 9:00 Breakfast Session V: Dust formation and evolution in massive galaxies (Chair: David Elbaz) 9:00 – 9:30 Moshe Elitzur* - Dust Formation -- Extreme and Non-Extreme

Environments

9:30 – 10:00 JD Smith* - Dust in Galaxies: Nuisance No Longer

10:00 – 10:30 Ranga Chary* - Studying Dust Grain Size Distribution With Redshift 10:30 – 10:50 Coffee Break 10:50 – 11:20 Eli Dwek* - The Origin of Dust in the High-Redshift Universe

11:20 – 12:00 Discussion led by Lee Armus 12:00 – 1:15 Lunch Session VI: Conference summary - future observational tests hybrid session (Chair: Alexandra Pope) 1:15 – 1:35 Sandy Faber* - Prospects For Observing Massive Galaxies in The

CANDELS Survey

1:35 – 1:55 Peter Eisenhardt* - Initial Results on Luminous Obscured Galaxies From the Wide-field Infrared Survey Explorer

1:55 – 2:15 Min Yun* - Future Observations of the Gas/Dust Content Evolution

2:15 – 2:35 Fabian Walter* – ALMA

2:35 – 2:55 Chris Carilli* - Gas and Dust in the First Galaxies 2:55 – 3:15 Coffee Break 3:15 – 4:00 Discussion led by Desika Narayanan * Invited Speaker

Posters Fuyan Bian

Near-IR Observations of the z~2 Lensed Galaxy J0900+2234 with LBT/LUCIFER Shane Bussmann The Nature of Dust-Obscured Galaxies at z~2 Jeyhan Kartaltepe A First Look at Galaxy Morphology at High-Redshift Using HST/WFC3 Imaging Katherine Kornei The Prevalence and Properties of Outflows at z=1 Mariska Kriek Towards more accurate properties of massive galaxies:

constraining the TP-AGB phase Matt Malkan Finding Red Galaxies at z>1.5: 3 Ways to Use Near-IR Surveys Efficiently Kyle Penner Origins of the Cosmic Millimeter Background Moire Prescott Testing Models of Lyα Nebulae George Rieke Evolution of IR Galaxy Star Forming Environment

SessionI:TalkAbstracts

Session I: Accretion Processes in Massive Galaxy Formation _________

Gas Accretion in Galaxies

Dusan Keres, ITC Harvard / TAC Berkeley - Invited

Most galaxies are actively star forming at all epochs. However, observations of cold gas reservoirs indicate that, at any epoch, there is not enough gas in dense galactic component to support evolution of star formation activity over time. This suggests that galactic gas is being replenished from the intergalactic medium. I use fully cosmological simulations of galaxy formation to study the gas supply into galactic component from high redshift to present. At high redshift "smooth" infall of cold filamentary gas dominates the gas supply of all galaxies. This "cold mode accretion" is a major driver of very active star formation of high-z galaxies enabling such activity to proceed for a significant fraction of the Hubble time. Gas accretion rates at a given halo and galaxy mass decrease with time, causing the drop in star formation rates. Properties and geometry of infalling gas change with halo mass and redshift. At low redshift some of the halos are able to cool hot virialized gas but filaments can also indirectly supply galaxies with gas via cold gaseous clouds that form from infalling cold/warm filamentary gas. In this talk I will describe properties, physics and consequences of gas accretion, and feedback processes needed to modulate growth of galaxies over time. Finally, I will point out promising directions for future research in this area and discuss several observational probes of cold halo gas that can provide strong constraints on the physics of gas accretion in galaxies.


Galaxy Mergers Through Cosmic Time Jennifer Lotz, STScI - Invited

Galaxies grow with time through both discrete galaxy mergers and smooth gas

accretion. When and how this growth occurs, and the role of mergers in defining the properties of today's galaxies, remain outstanding observational questions. I will review recent observational constraints on the frequency and importance of galaxy mergers at z< 1. New capabilities and surveys (e.g. CANDELS) will provide new opportunities for studying galaxy assembly at z>1. I will discuss these opportunities, and the challenges for identifying galaxy mergers in the early universe.


Feeding Massive Galaxies in their Most Active Phase of Assembly and Star Formation

Avishai Dekel, Hebrew University - Invited

Theory predicts a qualitative difference between the ways massive star-forming galaxies are fed at high and low redshifts. At z~2 and earlier, they are fed by intense narrow cold streams along the cosmic-web filaments, penetrating through a hot medium and outflowing gas. These incoming streams involve a broad spectrum of substructures, ranging from galaxies that lead to major and minor mergers to mini-minor clumps and smooth cold flows that carry more than half the mass. At low z, the input, by mergers and cold accretion, is expected to be at a much lower rate and from many directions. Re-entry of earlier outflows may play an important role at z~2 and later. Our challenges in the understanding of the most active phase of galaxy formation at high redshift include, for example, the following issues: 1. The interface between the incoming streams and the star-forming disk they feed, including the exchange of energy and angular momentum between the components, and the way the streams are halted and break up. 2. The generation of massive outflows. 3. The interaction between the incoming streams and the massive outflows, and the re-entry of outflows. 4. The development of wild disk instability, associated with rapid star formation in giant clumps, and the associated feedback effects. 5. Formation of compact spheroids by rapid mass inflows in the disk associated with the wild instability, in parallel to external mergers. 6. The evolution of high-z galaxies into the present-day population of galaxies.


The Efficiency of Clusters at Stopping Gas Accretion in Galaxies Gregory Rudnick, University of Kansas

Despite decades of work, it is still unclear whether a galaxy's properties are affected by environment or whether they are determined solely by the galaxy's mass. I will present new results that shed light on the key question of whether galaxies have their gas supplies cut off in dense environments. Addressing this problem observationally is key as environmental processes are only primitively modeled in theoretical studies. We make significant advances with respect to previous works by probing a large number of clusters (not available in DEEP2 or COSMOS), using precisely matched field samples, using deep Spitzer observations and multi-wavelength photometry to break the degeneracy between age and dust in galaxy colors, and using deep spectra of hundreds of cluster and field galaxies. After accounting for underlying trends with stellar mass we find significant environmental trends in the passive galaxy fraction and the fraction of galaxies with obscured star formation. Interestingly, galaxies that are dominated by old stellar populations are likely to have star formation and/or AGN activity if they are in the field, while galaxies with identical stellar populations in clusters have almost no activity. The difference in properties between the environments is very significant and implies that the cluster environment can cut off the gas supply to galaxies. I will discuss what process may be responsible for these trends and how these may change as one approaches the peak of the cosmic star formation history at higher redshift.


Discovery of Massive Amounts of Cold HI Gas in a Galaxy Overdensity at Redshift~1.6

Mauro Giavalisco, University Of Massachusetts Amherst

We report the discovery of large amounts of cold (T~104K) HI gas in an overdensity of galaxies at redshift z~1.6 located in the Great Observatories Origins Deep Survey southern field (GOODS-S). The gas is identified by the MgII λ2800 absorption features it imprints in the rest--frame UV spectra of background Lyman-break galaxies at z~. The lack of corresponding FeII absorption features, not detected even in a stacked spectrum, suggests that the gas is significantly less enriched than that observed in the outflows from star-forming galaxies at similar redshift. Four ultra strong MgII absorption lines, with rest-frame equivalent width W_r~6-8 ang, are observed in the spectra of three LBG, with one of them having two distinct absorption systems with centroids separated by about 3500 km/s. No galaxy with either spectroscopic or photometric redshift in the range 1.5<z<1.7 brighter than m4.5µm<23.0, roughly M*>4x109 M_sun at z=1.6, is observed within 220 kpc from the line of sight to any of the three LBG, implying that the optically-thick gas is not directly associated with any massive galaxy, but rather is “intracluster gas'' associated with the overdensity. The relatively high number of absorbers and the large spatial separation between them is consistent with the high-column density gas, very likely NH>=1020 cm-2. A lower limit to the HI mass of the individual absorbing trough based on the resolved nature of the galaxies is M>2.5x108x(NHI/1020) M_sun. This finding is the first direct evidence of “cold gas'' associated with large-scale structure at high redshift, and our methodology demonstrates that galaxy absorption systems provides a powerful, viable strategy, even with current technology, to investigate the occurrence of cold accretion in distant star-forming galaxies.

SessionII:TalkAbstracts

Session II: Star Formation in Massive Galaxies _________

What can be Learned from the Atomic and Molecular Gas Scaling

Relations of Nearby Galaxies? Guinevere Kauffmann, MPIA - Invited

I will present some highlights from GASS, the GALEX Arecibo SDSS Survey, as

well its sister survey COLD GASS. These surveys are characterizing the atomic and molecular hydrogen content of a sample of ~1000 nearby galaxies with stellar masses greater than 10^10 M_sol down to gas fraction limits of a few percent. These surveys will allow us to understand the balance between atomic and molecular gas in nearby galaxies, and how these gas properties scale with other global galaxy properties such as stellar masses and star formation rates. By studying outliers from the scaling relations between gas fraction and the stellar content of galaxies, we learn more about the processes that regulate accretion from the external environment and ongoing star formation in the present-day population.


On the Star Formation Rates and Star Formation Histories of Massive Galaxies

Casey Papovich, Texas A&M University - Invited

I will discuss constraints on the star formation rates (SFRs) and the star formation histories (SFHs) of massive galaxies at high redshifts. At z > 2, a variety of SFR indicators are now available from rest-frame UV, nebular emission lines, mid-IR, far-IR, and radio observations. I will compare observations of these various indicators, and I will offer some interpretation in the instances where they deviate. I will also discuss constraints on the SFHs of massive galaxies at z > 2. I will emphasize our study, which places empirical constraints on the evolution of the SFHs of massive galaxies at z > 2 using galaxy samples selected at constant (comoving) number density. I will argue that this selection allows us to track the evolution in the galaxies' progenitors and descendants at different redshifts, in strong contrast to samples selected at constant luminosity or mass. The SFHs of massive galaxies at these redshifts are best described by SFRs that increase as a power-law in time. This is in contrast to assumptions that the SFR is either constant or declines with time. This SFH for massive galaxies is reasonably consistent with the growth in stellar mass for galaxies from z~8 to z~2, and provides evidence that the high-mass end of the stellar IMF is approximately Salpeter, unless the duty cycle of star formation is much less than unity. Lastly, I will discuss how the empirically measured SFH and stellar mass growth make estimates for the gas fractions and on the role of gas accretion at these epochs.


Star Formation Modes in Distant Massive Galaxies Emanuele Daddi, CEA Saclay - Invited

I will report on our recent work, based largely on IRAM and Herschel, to

understand the nature of star formation in the distant universe and its relation with galaxy assembly.


The Contribution of Merger-Induced Starbursts to the Sub-millimeter Galaxy Population

Chris Hayward, CfA

Sub-millimeter galaxies (SMGs) are some of the most luminous, highly star-forming galaxies, with some SMGs having inferred star formation rates > 1000 solar masses per year. Consequently, SMGs enable study of extreme, possibly Eddington-limited star formation in massive galaxies at z ~ 2-4. One long-standing question is whether merger-induced starbursts can account for the observed number density of SMGs. Baugh et al. (2005) were able to produce sufficient SMGs in their semi-analytic model only by using a flat initial mass function (IMF) in merger-induced bursts of star formation. With this modification, merger-induced bursts constitute the bulk of the SMG population. Davé et al. (2010) present an alternative scenario in which most SMGs in their cosmological simulation are massive disks undergoing star formation fueled by cold flows rather than major mergers. However, the star formation rates of their simulated observations are ~3x lower than those inferred for observed SMGs; one potential way to reconcile this discrepancy is a top-heavy IMF. Here we present a novel, multi-scale approach to predict the number density of SMGs. We analyze a large suite of high-resolution gadget (Springel et al. 2005) n-body/smoothed-particle hydrodynamics simulations of isolated and merging disk galaxies with the 3-d Monte Carlo radiative transfer code sunrise (Jonsson 2006, Jonsson et al. 2010) in order to calculate spectral energy distributions of the simulated galaxies. This enables us to quantify the SMG duty cycle as a function of galaxy parameters (mass, merger mass ratio, and gas fraction). We then employ the semi-empirical merger rate model of Hopkins et al. (2008) to predict the SMG number counts. We show that in our model mergers are able to account for the observed SMG number densities even when we use a standard Kroupa IMF, with mergers being classified as SMGs both during the infall when the two galaxies are both in the ~150 kpc sub-mm beam and during the merger-induced burst.


WISE Selected Lyman-alpha Blobs at z~2 Carrie Bridge, Caltech

The NASA Wide Field Infrared Explorer (WISE) is an all-sky survey mission

imaging at 4 bands between 3.3 and 22 microns. A unique power of this mission is its ability to unveil some of the rarest most IR luminous objects in the universe. Using WISE colors, we serendipitously identified a population of z~2 IR luminous galaxies with Lyman alpha emission (LAE) which in some cases are Lyman alpha blobs (LABs). Unlike most optically selected LABs however, these WISE selected galaxies are massive ULIRG (L_IR > 10^12) and HyLIRGs (L_IR>10^13) in energetic phases of formation at a key epoch of galaxy and black hole growth. A third of the sample reside in the LAE pairs, and in one case Lyman alpha emission extends between the galaxies which are separated by ~40kpc. I will present the unique properties of this sample and discuss possible mechanisms for the extended Lyman alpha emission seen in these massive IR luminous galaxies.

SessionIII:TalkAbstracts

Session III: Role of AGN During Active, High SFR Phase _________

How do Massive Black Holes Get their Gas (and Get Rid of It)?

Phil Hopkins, UC Berkeley - Invited

Recent observations of tight correlations between supermassive black hole masses and the properties of their host galaxies demonstrate that black holes and bulges are co-eval, and have motivated theoretical models in which feedback from AGN activity regulates the black hole and host galaxy evolution. I’ll review the state of models and observations regarding quasar and AGN fueling and feedback, using new multi-scale simulations that can probe from galaxy scales down to the accretion disk. Combining simulations, analytic models, and recent observations, answers to a number of questions are starting to take shape: How to AGN get triggered? How long do they live? Are there relics in the local Universe -- perhaps even in M31 and the Milky Way -- that provide unique information on the epoch of black hole growth? Is feedback necessary/sufficient to regulate BH growth? What effects does that feedback have on the host galaxy? And how does this interact with the dynamics of stellar evolution and other sources of feedback in the ISM?


Feedback From Radiation Pressure During the Growth of Massive Galaxies and Their Central Black Holes

Eliot Quataert, UCLA Berkeley - Invited

The radiation produced by massive stars or an AGN can exert a strong feedback effect on ambient gas via the absorption and scattering of radiation by dust in the interstellar medium. I argue that this radiation pressure (i.e., momentum injection) is the most important form of feedback on dense gas in galaxies. Since it is the dense gas that fuels star formation and black hole growth, it is critical to understand the impact of radiation pressure on this gas. I summarize the effects of radiation pressure on both star formation and black hole growth during galaxy formation. I do so drawing on both analytic calculations and the results of numerical simulations of galaxy mergers that include phenomenological models of feedback by radiation pressure from a central AGN.


A Herschel View on Star Formation in High Redshift AGN Hosts Dieter Lutz, MPE - Invited

Host star formation rates are a key quantity in the (co)evolution of AGN and their

hosts but hard to measure. I will use mid-IR spectroscopic evidence to reconfirm the use of rest frame far-IR photometric measurements for quantifying star formation in high z AGN hosts. I will then use results from the first months of the Herschel mission as well as submm data from apex to map the star formation in high z AGN, outlining a picture combining two paths of AGN/host co-evolution. A correlation of AGN luminosity and host star formation is traced locally over a wide range of luminosities and also extends to luminous high z AGN. This correlation reflects an evolutionary connection, likely via merging. For lower AGN luminosities, star formation is similar to that in non-active massive galaxies and shows little dependence on AGN luminosity. The level of this secular, non-merger driven star formation increasingly dominates over the correlation at increasing redshift.


Linking Starbursts, Major Mergers, and Absorbed AGNs at z~0.7 Stéphanie Juneau, University of Arizona

I will present a detailed study of the occurrence of star formation, active galactic

nuclei (AGNs), and galaxy mergers in a sample of 70-micron selected galaxies from the Far-Infrared Deep Extragalactic Legacy survey (FIDEL). Deep multiwavelength observations reveal a complex connection between starburst, AGN, dust obscuration, and gas outflows. For galaxies with measureable emission lines, we show that the fraction of 70-micron galaxies with any level of AGN activity may be as high as 40-45%, i.e., more common than previously thought. This difference may be due to 70-micron galaxies hosting AGNs that are heavily absorbed (Compton-thick). I will present evidence that these systems are ideal test-beds for galaxy merger scenarios in which gas-rich galaxies merge, go through a deeply embedded ULIRG phase before emerging as an X-ray and optically identified AGN. Compiling galaxies at different evolutionary stages allows us to witness this process at redshift ~0.7. Lastly, I will highlight the potential of future multi-wavelength studies in constraining such evolutionary scenarios.


The Two Phase Evolution of Massive Galaxies Jeremiah P Ostriker, Princeton University

Cosmological simulations of galaxy formation appear to show a two-phase

character with a rapid early phase at z>2 during which in-situ stars are formed within (r~ 1kpc) the galaxy from infalling cold gas followed by an extended phase since z<3 during which ex-situ stars are primarily accreted. In the latter phase massive systems grow considerably in mass and radius by accretion of smaller satellite stellar systems formed at quite early times (z>3) outside of the virial radius of the forming central galaxy. These tentative conclusions are obtained from high resolution re-simulations of individual galaxies in a full cosmological context with present-day virial halo masses ~ 1012.5 M_sun and central galaxy masses ~1011.5 M_sun. The simulations include the effects of a uniform UV background, radiative cooling, star formation and energetic feedback from SNII. The importance of stellar accretion increases with galaxy mass and towards lower redshift. Lower mass galaxies accrete about 60 per cent of their present-day stellar mass. High mass galaxy assembly is dominated by accretion and merging with about 80 per cent of the stars added by the present-day. In general the simulated galaxies approximately double their mass since z=1, in agreement with current observations. This mass growth is not accompanied by significant star formation. The majority of the in-situ created stars is formed at z>2, primarily out of cold gas inflows. We recover the observational result of archaeological downsizing, where the most massive galaxies harbor the oldest stars and find that this is not in contradiction with hierarchical structure formation. Most stars in the massive galaxies are formed early on in smaller structures; the galaxies themselves are assembled late.

SessionIV:TalkAbstracts

Session IV: Internal Structure of Galaxies During High SFR Phase _________

Gas-rich Massive Disks at z~2

Reinhard Genzel, MPE & University of California, Berkeley - Invited

I report on two major programs of studying the kinematics, star formation and cold gas properties of z~2 massive star forming galaxies (z2SFGs) with spatially resolved spectroscopy. With the adaptive optics assisted, integral field spectrometer SINFONI on the ESO VLT we have studied about 90 z2SFGs and find compelling evidence for large, turbulent rotating disk galaxies in ~50% of the larger objects that we spatially resolve well. It appears plausible that these z2SFGs may be driven by continuous, rapid accretion of gas from their dark matter halos, and that their evolution is strongly influenced by internal, secular evolution. In a new program on the IRAM Plateau de Bure millimeter interferometer we have also detected for the first time CO 3-2 line emission in a sample of these z2SFGs (as well as in matched z~1.2 counterparts). We find that the z~1-2 SFGs are gas rich and that their star formation properties are fully compatible with a standard Kennicutt-Schmidt star formation relation. I will discuss the impact of these new observations on our understanding of galaxy evolution in the early Universe.


The Gas Consumption History Over Cosmic Times Leo Blitz, University of California, Berkeley - Invited

We investigate the rate at which galaxies consume their gas over lookback times

from z = 0 to z = 4 and conclude that the molecular and atomic gas content of the galaxies is insufficient to fuel the ongoing star formation. Based on the observations alone, we show that the fueling of the galaxies must ultimately be from the intergalactic ionized gas and that the atomic and ionized gas must be phases of the mass flow rather than reservoirs to fuel the star formation. We show and discuss evidence for continued gas accretion from early type galaxies, but cannot be sure if this is from accreted dwarf galaxies or from inflows such as "cold flows."


A Theoretical View on the Internal Structure of High Redshift Galaxies Thorsten Naab, MPIA - Invited

Massive star-forming galaxies at high redshift are observed to be gas rich, often

have extended disk-like and clumpy morphologies, and show evidence for strong outflows. High-resolution simulations indicate cold flows as an efficient gas supply mechanism. Strong feedback from supernovae might then play a decisive role on how efficient gas is transformed into stars and expelled from the galaxies. This process has a significant impact on the galaxy properties and the general baryon conversion efficiency. I will present recent progress – based on high-resolution cosmological simulations - on our theoretical understanding of the formation of star forming galaxies and their internal structure in the framework of the concordance cosmological model.


Cold Gas Inventories in Massive High-Redshift Galaxies Andrew Baker, Rutgers, The State University Of New Jersey

Characterizing the mode and efficiency of star formation in dusty high-redshift

galaxies requires that we accurately determine their total molecular gas masses. Typically, gas mass is estimated by scaling the observed luminosity of a mid-J CO rotational line to an expected CO(1-0) luminosity and then applying a "ULIRG" CO-to-H2 conversion factor that has been calibrated from z=0 datasets. New GBT/Zpectrometer detections of CO(1-0) emission from massive submillimeter galaxies (SMGs) suggest that common assumptions made when taking both of these steps may be suspect, and that total molecular gas masses in SMGs may be higher than previously thought. I will discuss an emerging "standard" picture of the molecular ISM in SMGs, featuring multiple thermalized phases with different filling factors, as well as indications that individual objects can still have properties deviating from the norm.


High Gas Fractions and the K-S Relation for "Normal" Star Forming Galaxies From z=1-3

Linda Tacconi, MPE

In an ongoing IRAM two-year large program, we are surveying the molecular gas contents and dynamics in two samples of typical massive-star-forming galaxies (SFGs) at redshifts of 1.2 and 2.3. With recent improvements in sensitivity at the PdB interferometer, we can detect co line emission from the massive tail of typical, SFGs at these epochs. The full sample comprises ~20 galaxies at each redshift range. The data reveal that SFGs are very gas rich, and that the star formation efficiency is not strongly dependent on cosmic epoch. The average fraction of cold gas relative to total galaxy baryonic mass at z = 2.3 and z = 1.2 is ~ 44% and 34%, respectively, three to ten times higher than in local spiral galaxies. A slow decrease from z≈2 and z≈1 likely requires semi-continuous replenishment of fresh gas to the young galaxies. We also discuss the Kennicutt-Schmidt relation for SFGs at both low and high redshift. SFG galaxy populations appear to follow a molecular gas-star formation relation with slope 1.1 to 1.2, over three orders of magnitude in gas mass or surface density.

SessionV:TalkAbstracts

Session V: Dust Formation and Evolution in Massive Galaxies _________

Dust Formation -- Extreme and Non-Extreme Environments

Moshe Elitzur, University of Kentucky - Invited

Where and how does dust form? There's observational evidence for dust formation less than 1 Gyr after the big-bang as well as right in front of our eyes. In this talk I will try to tie together the different pieces of evidence.


Dust in Galaxies: Nuisance No Longer JD Smith, University Of Toledo - Invited

Dust represents less than one-hundredth of one percent of the mass of a typical

galaxy, yet is responsible for reprocessing on average one-half of all the luminous energy arising from star formation and accretion within them. I'll review the recent successes and promising future of dust as a tool to study galaxy evolution, including its role as the primary heating agent of the interstellar medium, its unique responses to stellar vs. non-stellar power sources, the potential for using dust as a sensitive tracer of the total gas reservoir, and the ongoing efforts to obtain an accurate census of the dust content of massive galaxies in the local universe.


Studying Dust Grain Size Distribution With Redshift Ranga Chary, Caltech - Invited

Measuring the size distribution of dust grains in galaxies is a challenge. The observables that trace the size distribution are 1) the relative amount of mid- to far-infrared emission, 2) the color temperature of the far-infrared emission and 3) the dust extinction curve especially in the UV. I will present evidence for an evolution in these observables with redshift and assess if these can be reproduced by a change in grain size distribution.


The Origin of Dust in the High-Redshift Universe Eli Dwek, NASA Goddard Space Flight Center - Invited

Two distinct scenarios for the origin of the dust observed in the high-redshift (z =

6.4) quasar J1148+5251 have been proposed. The first assumes that this galaxy is much younger than the age of the universe at that epoch so that only supernovae (SNe) could have produced this dust. The second scenario assumes a significantly older galactic age, so that the dust could have formed in lower-mass asymptotic giant branch (AGB) stars. The two scenarios propose different origins for the galaxy's spectral energy distribution, different stellar masses, and consequently different comoving number densities of J1148-type hyperluminous infrared (IR) objects. In this talk I will offer a critical evaluation of these two scenarios, and further observational consequences that can discriminate between the two.

SessionVI:TalkAbstracts

Session VI: Conference Summary – Future Observational Tests Hybrid Session

_________

Prospects For Observing Massive Galaxies in The CANDELS Survey Sandra Faber, University of California, Santa Cruz - Invited

The Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS,

http://csmct.ucolick.org/) is a Hubble Space Telescope Multi-Cycle Treasury project awarded 902 orbits with WFC3 and ACS during 2010-2013. CANDELS will obtain data on 250,000 galaxies to complete Hubble's legacy in the area of deep lookback observations of galaxy evolution. A time-domain search will discover Type Ia supernovae at z>1.5 to determine their progenitors and possible evolution. The Deep survey covers ~0.04 deg2 in the GOODS fields to a 5-sigma AB depth of H=28, including UV data in GOODS-N. The Wide survey covers ~0.2 deg2 to H=27 in the same fields plus COSMOS, EGS, and UDS and is tuned to study rarer objects such as massive galaxies and AGN. I will show examples of WFC3 and ACS data on galaxies at various redshifts and describe our team's early attempts to characterize and quantify their structure.


Initial Results on Luminous Obscured Galaxies From the Wide-field Infrared Survey Explorer

Peter Eisenhardt, JPL - Invited

NASA’s Wide-Field Infrared Survey Explorer (WISE) launched on 2009 Dec. 14, and completed its first survey of the sky on 2010 July 17. The survey is achieving 5 sigma point source sensitivities of approximately 0.08, 0.1, 1, and 6 mJy or better in unconfused regions at 3.4, 4.6, 12, and 22 microns, and the spatial resolution is 6 arcsec FWHM (12 arcsec at 22 microns). WISE continued to survey the sky a second time until the cryogen was fully exhausted at the end of September. Surveying in the two shorter bands is expected to continue through January. The preliminary data release including the first 55% of the sky surveyed is planned for April 2011, and the final cryogenic survey release will be 11 months later (~ March 2012). The final source catalog will contain hundreds of millions of objects. A key scientific objective of the survey is to identify the most luminous, dusty, star forming galaxies in the universe. I will present some initial extragalactic results from WISE, ranging from local compact star-forming galaxies to hyper-luminous IR galaxies at z > 3.


Future Observations of the Gas/Dust Content Evolution Min Yun, University of Massachusetts - Invited

It is widely appreciated that gas accretion plays an important role in the stellar

mass build-up and possibly the AGN activities over cosmic time. Measuring the cold gas content has been one of the most difficult observational challenges, however. Spitzer and Herschel have already begun the census of warm and cold dust content for galaxies near and far, and the measurements of the dust content as a proxy for gas mass is beginning to yield a first glimpse on the gas content evolution for massive galaxies. An array of new facilities and experiments specifically designed to measure the cold atomic and molecular gas content will come on line during the next decade, and I will review their progress and prospect of charting the cold gas content evolution.


ALMA Fabian Walter, MPIA - Invited

Observations with ALMA will revolutionize our understanding of the physics of

the interstellar medium (in particular molecules and dust emission) at high redshift. With its unprecedented resolving power and sensitivity, ALMA will enable detailed morphological and dynamical studies of key molecular and atomic lines in distant galaxies. It will also enable resolved measurements of star formation, through high-resolution imaging of the (rest-frame) FIR emission, in high-redshift galaxies and quasars. It is currently envisioned that 'early science' will start in 2011, while the full ALMA array will be completed a few years later. I will discuss ALMA's 'early' and 'full' capabilities, with a particular focus on their impact on high-redshift studies of massive galaxies.


Gas and Dust in the First Galaxies Chris Carilli, NRAO - Invited

I will discuss recent observations of the cold molecular and atomic gas, dust, and

star formation in z>6 galaxies, and the promise of ALMA and the EVLA.

PosterAbstracts

Near-IR Observations of the z~2 Lensed Galaxy J0900+2234 with LBT/LUCIFER

Fuyan Bian, Steward Observatory, University of Arizona

We present rest-frame optical images and spectra of the lensed galaxy SDSS J0900+2234 (z=2.03). The observations were performed with the newly commissioned LUCIFER1 near-infrared (NIR) instrument mounted on the Large Binocular Telescope (LBT). Using the high S/N rest-frame spectra covering H+K band, we detected Hβ, [OIII], Hα, [NII], and [SII] emission lines. Detailed physical properties of this high-z galaxy were derived. The extinction towards the ionized HII regions (E_g(B-V)) was computed from the flux ratio of Hα and Hβ, much higher than that towards stellar continuum (E_s(B-V)), derived from the optical and NIR broad band photometry fitting. The metallicity is in the range of 1/5-1/3 solar abundance, which is much lower than the typical z~2 star-forming galaxies. We found that the electron number density of the HII regions in the high-z galaxy were ~1000cm-3, consistent with other z~2 galaxies. The star-formation rate was estimated via the Hα luminosity, after correction for the lens magnification, to be about 365±69 M_sun yr-1. Combining the FWHM of Hα emission lines and the half-light radius, we found the dynamical mass of the lensed galaxy is (5.8±0.9)x1010 M_sun. The gas mass is (5.1±1.1)x1010M_sun from the Hα flux surface density by using global Kennicutt-Schmidt Law, indicating a very high gas fraction of 0.79±0.19 in J0900+2234.

PosterAbstracts

The Nature of Dust-Obscured Galaxies at z~2 Shane Bussmann, CfA

I present a study of the stellar masses and star-formation histories of DOGs, using

stellar population synthesis models and broad-band photometry in the rest-frame ultra-violet, optical, and near-IR. The best-fit quantities indicate DOGs have masses similar to SMGs (median stellar masses of about 1010.7), with a tentative suggestion that SMGs are less massive than bump DOGs, which are less massive than power-law DOGs. The relatively low stellar masses found from this line of analysis favor a merger-driven origin over more quiescent star formation histories for ULIRGs at redshifts of about 2.

PosterAbstracts

A First Look at Galaxy Morphology at High-Redshift Using HST/WFC3 Imaging

Jeyhan Kartaltepe, NOAO

We present initial results from a morphological analysis of ~300 BzK selected galaxies in GOODS-S using the Early Release Science (ERS) WFC3 images taken with HST in conjunction with previously obtained ACS images. By studying the morphologies of these high redshift (z~2) in the near-infrared, we are actually probing rest-frame optical at high resolution. We use this rich data set to explore the morphological k-corrections present in this high-redshift sample of massive star-forming galaxies. Finally, we study the relationship between a galaxy's morphology and its position on the mass-star formation rate plane. In particular, we study the position of galaxies identified as possible mergers.

PosterAbstracts

The Prevalence and Properties of Outflows at z = 1 Katherine Kornei, UCLA

Outflowing winds have been observed in galaxies at a variety of redshifts and are

thought to play an important role in both the quenching of star formation and the enrichment of the intergalactic medium. We present the results of a study at z = 1 tracing the prevalence and properties of outflows in a sample of DEEP2 objects with rest-frame UV spectroscopy and HST optical imaging. We investigate if a critical star formation rate surface density is required to drive outflows, using a new technique for estimating galaxy area based on a physically motivated luminosity threshold. Previous work has suggested that the star formation rate surface density may be most strongly correlated with outflows (as opposed to the star formation rate); our method of estimating the area over which star formation is occurring represents an improvement over the simple adoption of a Petrosian or half-light radius. We discuss fine structure FeII emission in light of galaxy properties and investigate the likely origin of these features (which are not commonly observed in local starbursts). By conducting analyses on a per-object basis at z = 1, we are able to examine the relationship between outflow properties and individual galaxy morphology, stellar populations, and star formation surface density, at the epoch when the global star formation rate is beginning its decline to the present day.

PosterAbstracts

Towards more accurate properties of massive galaxies: constraining the TP-AGB phase

Mariska Kriek, Princeton

In our quest for understanding the growth of massive galaxies, it is fundamental to accurately determine stellar masses and other galaxy properties. However, with the recent instrumental advances, the stellar population synthesis (SPS) models currently lack behind the observations, and systematic uncertainties limit our understanding. Of particular concern is the treatment of the thermally-pulsing asymptotic giant branch (TP-AGB) phase, as different implementations in SPS models lead to large systematic differences in derived galaxy properties. Post-starburst galaxies are a promising calibration sample, as TP-AGB stars are thought to be most prominently visible during this phase. We have used post-starburst galaxies in the NEWFIRM Medium-Band Survey to assess SPS models and constrain the TP-AGB phase. Interestingly, our data demand a very low contribution from TP-AGB stars to the near-infrared spectrum. This may be due to lower bolometric luminosities, shorter lifetimes, and/or heavy dust obscuration of TP-AGB stars. To obtain more detailed information, we are currently conducting a near-infrared spectroscopic survey of low-redshift post-starburst galaxies. I will present our findings and discuss the implications for our understanding of the massive galaxy growth.

PosterAbstracts

Finding Red Galaxies at z>1.5: 3 Ways to Use Near-IR Surveys Efficiently

Matt Malkan, UCLA

You already know the first one, the tried-and-true BzK two-color plot. With our deep multiwavelength imaging of the Subaru Deep Field, we have compared the BzK galaxies with all the other 1.5<z<3 galaxies we can find using other methods, mostly based on the rest-frame UV continuum. Except for the most strongly star-forming (bluest) galaxies, BzK does a good job, if the K band imaging is deep enough. It misses some very red galaxies. If you have only 3—5um imaging from space, but lack 1—2um data from the ground, a new roughly analogous two color method is rzL. Using thousands of galaxies with confidently estimated redshifts in COSMOS, I show that the rzL method captures a large fraction of z>1.5 galaxies, while suffering only minimal contamination from z<1.5 interlopers. Finally, our WFC3 Infrared Spectroscopic Parallels Survey (WISPS) has obtained continuous 0.8—1.7um grism spectra of thousands of galaxies in random blank fields. The low-resolution (R~200) spectra reveal many blue breaks or roll-offs that can be quantitatively matched with Balmer or HK/4000Angstrom absorption at redshifts of 1 to 2.5.

PosterAbstracts

Origins of the Cosmic Millimeter BackgroundKyle Penner, University of Arizona

The cosmic infrared background (CIB) is a present day measurement of dust

emission from all galaxies in the Universe. Resolving the background into individual galaxies with known redshifts constrains the output of dust obscured AGN activity and star formation over cosmic time. We average the 1mm flux densities of galaxies with detected 24um emission, and resolve 31--45% of the 1mm background. These galaxies resolve 40--64% of the background at 850um. We predict that 60--88% of the total background at 1mm comes from galaxies at z > 1.3. A numerous population of dusty, high redshift galaxies lurks below our current detection thresholds at (sub)millimeter wavelengths.

PosterAbstracts

Testing Models of Lyα Nebulae Moire Prescott, UC Santa Barbara

Lya nebulae are an important but poorly understood piece of the galaxy formation

puzzle. Boasting overdense environments, powerful Lya emission that extends out to 100 kpc scales, and a close association with strong submillimeter and mid-infrared sources, giant Lya nebulae offer a window into ongoing episodes of massive galaxy formation. In this context, understanding what is powering the Lya emission can provide insight into the dominant physical processes at work. In the last few years, substantial progress has been made towards building a theoretical framework for studying Lya nebulae. In light of the increasingly sophisticated simulations of cold flows, outflows, and Lya fluorescence that are now on the market, the time is ripe for making more detailed comparisons with the observations of Lya nebulae that have been coming in over the last decade. In this work, we present improved measurements of the morphology and energetics of a typical Lya nebula system and use them to test predictions from the superwind outflows and cold flow models. We find robust discrepancies between the morphology predicted by simulations in both cases. Even under the most optimistic simulated conditions, the Lya size and profile shape are substantially underestimated in cold flow models, and the relative positions of compact sources within the system differ substantially from predictions of both the cold flow and outflow scenarios. Yet both of these phenomena have been shown to play an important role in the accretion of gas onto galaxies and in the distribution of metals in the universe - and must be going on at some level within these massive systems. Thus it appears likely that Lya nebulae are a decidedly composite phenomena - powered by and representative of a blend of physical processes in the formation of massive galaxies. Lya nebulae span a range of sizes and luminosities - from slightly extended halos around normal star-forming galaxies to the most luminous Lya nebulae - suggesting that different processes may dominate depending on, e.g., the luminosity, size, morphology, or halo mass of the system. To disentangle this, we argue that it is time to investigate the physical conditions within Lya nebulae using emission line diagnostics and to consider the energetics of Lya nebulae across the entire ensemble. To this end, we use simple observational metrics to investigate the relationship between different Lya nebulae (as well as their close cousins, the emission line halos around radio galaxies) and discuss what this may reveal about the process of massive galaxy formation in these regions.

PosterAbstracts

Evolution of IR Galaxy Star Forming Environment George Rieke, Steward Observatory

We show that the sizes of the star-forming regions in high redshift, very

luminous, infrared galaxies are much larger than the sizes of such regions in typical local galaxies of similar luminosity. If the luminosity surface density is used to select SED templates, then the high redshift galaxy templates behave to first order as those of local galaxies do. There is a well-defined relationship between total infrared luminosity and luminosity surface density if one excludes the local LIRGs and ULIRGs. This relation can be used to derive accurate star forming rates even from single-band infrared photometry (e.g., at 24 microns).

ParticipantList

Name Affiliation Email

Lee Armus SSC [email protected] Andrew Baker Rutgers [email protected] Fuyan Bian Steward Observatory [email protected] Leo Blitz University of California Berkeley [email protected] Nicolas Bouché University of California Santa Barbara [email protected] Frédéric Bournaud CEA Saclay [email protected] Carrie Bridge Caltech [email protected] Mark Brodwin CfA [email protected] Alyson Brooks Caltech [email protected] Shane Bussmann CfA [email protected] Chris Carilli NRAO [email protected] Ranga Chary Caltech [email protected] Kristen Coppin Mcgill University [email protected] Darren Croton Swineburne University [email protected] Emanuele Daddi CEA Saclay [email protected] Avishai Dekel Hebrew University [email protected] Vandana Desai SSC [email protected] Arjun Dey NOAO [email protected] Mark Dickinson NOAO [email protected] Eli Dwek NASA Goddard [email protected] Peter Eisenhardt JPL [email protected] David Elbaz CEA Saclay [email protected] Moshe Elitzur University of Kentucky [email protected] Sandra Faber University of California Santa Cruz [email protected] David Frayer NRAO [email protected] Jared Gabor University of Arizona [email protected] Reinhard Genzel MPE [email protected] Mauro Giavilisco University of Massachusetts [email protected] Chris Hayward CfA [email protected] Timothy Heckman Johns Hopkins [email protected] Phil Hopkins University of California Berkeley [email protected] Buell Jannuzi NOAO [email protected] Stéphanie Juneau Steward Observatory [email protected] Jeyhan Kartaltepe NOAO [email protected] Guinevere Kauffmann MPIA [email protected] Dusan Keres University of California Berkeley [email protected] Katherine Kornei UCLA [email protected] Mariska Kriek CfA [email protected] Tod R. Lauer NOAO [email protected] Jennifer Lotz STScI [email protected] Dieter Lutz MPE [email protected] Matt Malkan UCLA [email protected] Gaelen Marsden University of British Columbia [email protected] Jason Melbourne Caltech [email protected] Leonidas Moustakas JPL/Caltech [email protected] Thorsten Naab MPIA [email protected] Desika Narayanan University of Arizona [email protected] Jeremiah Ostriker Princeton University [email protected]

ParticipantList

Casey Papovich Texas A&M [email protected] Kyle Penner University of Arizona [email protected] Alexandra Pope University of Massachusetts [email protected] Moire Prescott University of California Santa Barbara [email protected] Eliot Quataert University of California Berkeley [email protected] George Rieke University of Arizona [email protected] Greg Rudnick University of Kansas [email protected] Nick Scoville Caltech [email protected] JD Smith University of Toledo [email protected] Rachel Somerville STScI/JHU [email protected] Linda Taconni MPE [email protected] Kim-Vy Tran Texas A&M [email protected] Fabian Walter MPIA [email protected] Benjamin Weiner University of Arizona [email protected] Min Yun University of Massachusetts [email protected] Cover art by Peter Marenfeld (NOAO)

Documents

Massive Galaxies Over Cosmic Time 3 - National … Galaxies Over Cosmic Time 3 The Role of Gas and Dust National Optical Astronomy Observatory Association of Universities for Research