A. Omont

Phibss: Molecular Gas Content and Scaling Relations in z ~ 1-3 Massive, Main-sequence Star-forming Galaxies

We present PHIBSS, the IRAM Plateau de Bure high-z blue sequence CO 3-2 survey of the molecular gas properties in massive, main-sequence star-forming galaxies (SFGs) near the cosmic star formation peak. PHIBSS provides 52 CO detections in two redshift slices at z ~ 1.2 and 2.2, with log(M *(M ☉)) ≥ 10.4 and log(SFR(M ☉/yr)) ≥ 1.5. Including a correction for the incomplete coverage of the M* -SFR plane, and adopting a Galactic value for the CO-H2 conversion factor, we infer average gas fractions of ~0.33 at z ~ 1.2 and ~0.47 at z ~ 2.2. Gas fractions drop with stellar mass, in agreement with cosmological simulations including strong star formation feedback. Most of the z ~ 1-3 SFGs are rotationally supported turbulent disks. The sizes of CO and UV/optical emission are comparable. The molecular-gas-star-formation relation for the z = 1-3 SFGs is near-linear, with a ~0.7 Gyr gas depletion timescale; changes in depletion time are only a secondary effect. Since this timescale is much less than the Hubble time in all SFGs between z ~ 0 and 2, fresh gas must be supplied with a fairly high duty cycle over several billion years. At given z and M *, gas fractions correlate strongly with the specific star formation rate (sSFR). The variation of sSFR between z ~ 0 and 3 is mainly controlled by the fraction of baryonic mass that resides in cold gas.

High-Resolution Millimeter Imaging of Submillimeter Galaxies*

We present ~06 resolution IRAM PdBI interferometry of eight submillimeter galaxies at z ~ 2-3.4, where we detect continuum at 1 mm and/or CO lines at 3 and 1 mm. The CO 3-2/4-3 line profiles in five of the sources are double-peaked, indicative of orbital motion either in a single rotating disk or of a merger of two galaxies. The millimeter line and continuum emission is compact; we marginally resolve the sources or obtain tight upper limits to their intrinsic sizes in all cases. The median FWHM diameter for these sources and the previously resolved sources, SMM J023952-0136 and SMM J140104+0252, is ≤05 (4 kpc). The compactness of the sources does not support a scenario in which the far-IR/submillimeter emission comes from a cold (T < 30 K), very extended dust distribution. These measurements clearly show that the submillimeter galaxies (SMGs) we have observed resemble scaled-up and more gas-rich versions of the local universe, ultraluminous galaxy population. Their central densities and potential well depths are much greater than those in other z ~ 2-3 galaxy samples studied so far. They are comparable to those of elliptical galaxies or massive bulges. The SMG properties fulfill the criteria of maximal starbursts, in which most of the available initial gas reservoir of 1010-1011 M☉ is converted to stars on a timescale ~3-10tdyn ~ a few times 108 yr.We present sub-arcsecond resolution IRAM PdBI interferometry of eight submillimeter galaxies at redshifts from 2 to 3.4, where we detect continuum at 1mm and/or CO lines at 3 and 1 mm. The CO 3-2/4-3 line profiles in five of the sources are double-peaked, indicative of orbital motion either in a single rotating disk or of a merger of two galaxies. The millimeter line and continuum emission is compact; we marginally resolve the sources or obtain tight upper limits to their intrinsic sizes in all cases. The median FWHM diameter for these sources and the previously resolved sources, SMMJ023952-0136 and SMMJ140104+0252 is less than or equal to 0.5(4 kpc). The compactness of the sources does not support a scenario where the far-IR/submm emission comes from a cold, very extended dust distribution. These measurements clearly show that the submillimeter galaxies we have observed resemble scaled-up and more gas rich versions of the local Universe, ultra-luminous galaxy (ULIRG) population. Their central densities and potential well depths are much greater than in other redshift 2-3 galaxy samples studied so far. They are comparable to those of elliptical galaxies or massive bulges. The SMG properties fulfill the criteria of maximal starbursts, in which most of the available initial gas reservoir of 10^10-10^11 solar masses is converted to stars on a few dynamical timescales.

Herschel-ATLAS: A binary HyLIRG pinpointing a cluster of starbursting protoellipticals

Panchromatic observations of the best candidate hyperluminous infrared galaxies from the widest Herschel extragalactic imaging survey have led to the discovery of at least four intrinsically luminous z = 2.41 galaxies across an 100 kpc region—a cluster of starbursting protoellipticals. Via subarcsecond interferometric imaging we have measured accurate gas and star formation surface densities. The two brightest galaxies span ~3 kpc FWHM in submillimeter/radio continuum and CO J = 4-3, and double that in CO J = 1-0. The broad CO line is due partly to the multitude of constituent galaxies and partly to large rotational velocities in two counter-rotating gas disks—a scenario predicted to lead to the most intense starbursts, which will therefore come in pairs. The disks have M_(dyn) of several × 10^(11) M ☉, and gas fractions of ~40%. Velocity dispersions are modest so the disks are unstable, potentially on scales commensurate with their radii: these galaxies are undergoing extreme bursts of star formation, not confined to their nuclei, at close to the Eddington limit. Their specific star formation rates place them 5 × above the main sequence, which supposedly comprises large gas disks like these. Their high star formation efficiencies are difficult to reconcile with a simple volumetric star formation law. N-body and dark matter simulations suggest that this system is the progenitor of a B(inary)-type 10^(14.6)-M ☉ cluster.

The Herschel Multi-tiered Extragalactic Survey: SPIRE–mm photometric redshifts

We investigate the potential of submmmm and submmmmradio photometric redshifts using a sample of mm-selected sources as seen at 250, 350 and 500 mu m by the SPIRE instrument on Herschel. From a sample of 63 previously identified mm sources with reliable radio identifications in the Great Observatories Origins Deep Survey North and Lockman Hole North fields, 46 (73 per cent) are found to have detections in at least one SPIRE band. We explore the observed submm/mm colour evolution with redshift, finding that the colours of mm sources are adequately described by a modified blackbody with constant optical depth tau=(/nu0)beta, where beta=+1.8 and nu 0=c/100 mu m. We find a tight correlation between dust temperature and IR luminosity. Using a single model of the dust temperature and IR luminosity relation, we derive photometric redshift estimates for the 46 SPIRE-detected mm sources. Testing against the 22 sources with known spectroscopic or good quality optical/near-IR photometric redshifts, we find submm/mm photometric redshifts offer a redshift accuracy of vertical bar Delta z vertical bar/(1+z)= 0.16 (textlessvertical bar Delta z vertical bar textgreater=0.51). Including constraints from the radiofar-IR correlation, the accuracy is improved to vertical bar Delta z vertical bar/(1+z)=0.15 (textlessvertical bar Delta z vertical bar textgreater=0.45). We estimate the redshift distribution of mm-selected sources finding a significant excess at z textgreater 3 when compared to similar to 850 mu m selected samples.

A Search for Dense Molecular Gas in High-Redshift Infrared-Luminous Galaxies

We present a search for HCN emission from four high redshift far infrared (IR) luminous galaxies. Current data and models suggest that these high

THE SPACE DENSITY OF LUMINOUS DUSTY STAR-FORMING GALAXIES AT z > 4: SCUBA-2 AND LABOCA IMAGING OF ULTRARED GALAXIES FROM HERSCHEL-ATLAS

z

Imaging the environment of A z = 6.3 submillimeter galaxy with scuba-2

IR luminous galaxies represent a major starburst phase in the formation of spheroidal galaxies, although many of the sources also host luminous active galactic nuclei (AGN), such that a contribution to the dust heating by the AGN cannot be precluded. HCN emission is a star formation indicator, tracing dense molecular hydrogen gas within star-forming molecular clouds (n(H

The most distant, luminous, dusty star-forming galaxies : redshifts from NOEMA and ALMA spectral scans

_2

Radio and Millimeter Observations of z ∼ 2 Luminous QSOs

)

Limits on dust emission from z similar to 5 LBGs and their local environments

sim 10^5