J. Ruel

ALMA REDSHIFTS OF MILLIMETER-SELECTED GALAXIES FROM THE SPT SURVEY: THE REDSHIFT DISTRIBUTION OF DUSTY STAR-FORMING GALAXIES

Using the Atacama Large Millimeter/submillimeter Array, we have conducted a blind redshift survey in the 3 mm atmospheric transmission window for 26 strongly lensed dusty star-forming galaxies (DSFGs) selected with the South Pole Telescope. The sources were selected to have S_(1.4mm) > 20 mJy and a dust-like spectrum and, to remove low-z sources, not have bright radio (S_843MHz) 3. We discuss the effect of gravitational lensing on the redshift distribution and compare our measured redshift distribution to that of models in the literature.

A massive, cooling-flow-induced starburst in the core of a luminous cluster of galaxies

In the cores of some clusters of galaxies the hot intracluster plasma is dense enough that it should cool radiatively in the cluster’s lifetime, leading to continuous ‘cooling flows’ of gas sinking towards the cluster centre, yet no such cooling flow has been observed. The low observed star-formation rates and cool gas masses for these ‘cool-core’ clusters suggest that much of the cooling must be offset by feedback to prevent the formation of a runaway cooling flow. Here we report X-ray, optical and infrared observations of the galaxy cluster SPT-CLJ2344-4243 (ref. 11) at redshift z = 0.596. These observations reveal an exceptionally luminous (8.2 × 1045 erg s−1) galaxy cluster that hosts an extremely strong cooling flow (around 3,820 solar masses a year). Further, the central galaxy in this cluster appears to be experiencing a massive starburst (formation of around 740 solar masses a year), which suggests that the feedback source responsible for preventing runaway cooling in nearby cool-core clusters may not yet be fully established in SPT-CLJ2344-4243. This large star-formation rate implies that a significant fraction of the stars in the central galaxy of this cluster may form through accretion of the intracluster medium, rather than (as is currently thought) assembling entirely via mergers.

SPT-CL J0546-5345: A Massive z > 1 Galaxy Cluster Selected Via the Sunyaev-Zel'dovich Effect with the South Pole Telescope

United States. National Aeronautics and Space Administration (Jet Propulsion Laboratory (U.S.))

X-RAY EMISSION FROM TWO INFRARED-SELECTED GALAXY CLUSTERS AT z > 1.4 IN THE IRAC SHALLOW CLUSTER SURVEY

We report the X-ray detection of two z > 1.4 infrared-selected galaxy clusters from the IRAC Shallow Cluster Survey (ISCS). We present new data from the Hubble Space Telescope and the W. M. Keck Observatory that spectroscopically confirm cluster ISCS J1432.4+3250 at z = 1.49, the most distant of 18 confirmed z > 1 clusters in the ISCS to date. We also present new spectroscopy for ISCS J1438.1+3414, previously reported at z = 1.41, and measure its dynamical mass. Clusters ISCS J1432.4+3250 and ISCS J1438.1+3414 are detected in 36 ks and 143 ks Chandra exposures at significances of 5.2{sigma} and 9.7{sigma}, from which we measure total masses of log (M{sub 200,L{sub X}}/M{sub sun}) = 14.4 {+-} 0.2 and 14.35 {sup +0.14}{sub -0.11}, respectively. The consistency of the X-ray and dynamical properties of these high-redshift clusters further demonstrates that the ISCS is robustly detecting massive clusters to at least z = 1.5.

Mass Calibration and Cosmological Analysis of the SPT-SZ Galaxy Cluster Sample Using Velocity Dispersion σ v and X-Ray Y X Measurements

We present a velocity dispersion-based mass calibration of the South Pole Telescope SunyaevZel’dovich eect survey (SPT-SZ) galaxy cluster sample. Using a homogeneously selected sample of 100 cluster candidates from 720 deg 2 of the survey along with 63 velocity dispersion ( v) and 16 X-ray YX measurements of sample clusters, we simultaneously calibrate the mass-observable relation and constrain cosmological parameters. Our method accounts for cluster selection, cosmological sensitivity, and uncertainties in the mass calibrators. The calibrations using v and YX are consistent at the 0:6 level, with the v calibration preferring 16% higher masses. We use the full SPTCL dataset (SZ clusters+ v+YX) to measure 8( m=0:27) 0:3 = 0:809 0:036 within a at CDM model. The SPT cluster abundance is lower than preferred by either the WMAP9 or Planck+WMAP9 polarization (WP) data, but assuming the sum of the neutrino masses is P m = 0:06 eV, we nd the datasets to be consistent at the 1.0 level for WMAP9 and 1.5 for Planck+WP. Allowing for larger P m further reconciles the results. When we combine the SPTCL and Planck+WP datasets with information from baryon acoustic oscillations and supernovae Ia, the preferred cluster masses are 1:9 higher than the YX calibration and 0:8 higher than the v calibration. Given the scale of these shifts ( 44% and 23% in mass, respectively), we execute a goodness of t test; it reveals no tension, indicating that the best-t model provides an adequate description of the data. Using the multi-probe dataset, we measure m = 0:299 0:009 and 8 = 0:829 0:011. Within a CDM model we nd P m = 0:148 0:081 eV. We present a consistency test of the cosmic growth rate using SPT clusters. Allowing both the growth index and the dark energy equation of state parameter w to vary, we nd = 0:73 0:28 and w = 1:007 0:065, demonstrating that the expansion and the growth histories are consistent with a

Submillimeter observations of millimeter bright galaxies discovered by the south pole telescope

We present APEX SABOCA 350 μm and LABOCA 870 μm observations of 11 representative examples of the rare, extremely bright (_( 1.4 mm) > 15 mJy), dust-dominated millimeter-selected galaxies recently discovered by the South Pole Telescope. All 11 sources are robustly detected with LABOCA with 40 mJy 3σ, with the detections or upper limits providing a key constraint on the shape of the spectral energy distribution (SED) near its peak. We model the SEDs of these galaxies using a simple modified blackbody and perform the same analysis on samples of SMGs of known redshift from the literature. These calibration samples inform the distribution of dust temperature for similar SMG populations, and this dust temperature prior allows us to derive photometric redshift estimates and far-infrared luminosities for the sources. We find a median redshift of z = 3.0, higher than the z = 2.2 inferred for the normal SMG population. We also derive the apparent size of the sources from the temperature and apparent luminosity, finding them to appear larger than our unlensed calibration sample, which supports the idea that these sources are gravitationally magnified by massive structures along the line of sight.

SPT-GMOS: A Gemini/GMOS-South Spectroscopic Survey of Galaxy Clusters in the SPT-SZ Survey

National Science Foundation [AST-1009012, PHY-1125897]; Kavli Foundation; Gordon and Betty Moore Foundation [GBMF 947]; NSF [AST-1009649, MRI-0723073]; Alfred P. Sloan Foundation; U.S. Department of Energy [DE-AC02-06CH11357]; Fermi Research Alliance, LLC [DE-AC02-07CH11359]; United States Department of Energy; NASA through Space Telescope Science Institute [HST-GO-13412.004-A]; NASA [NAS 5-26555]; [GS-2011A-C-03]; [GS-2011A-C-04]; [GS-2011B-C-06]; [GS-2011B-C-33]; [GS-2012A-Q-04]; [GS-2012A-Q-37]; [GS-2012B-Q-29]; [GS-2012B-Q-59]; [GS-2013A-Q-05]; [GS-2013A-Q-45]; [GS-2013B-Q-25]; [GS-2013B-Q-72]; [GS-2014B-Q-31]; [GS-2014B-Q-64]; [13412]

Optical followup of galaxy clusters detected by the South Pole Telescope

The South Pole Telescope (SPT) is a 10 meter telescope operating at mm wavelengths. It has recently completed a three-band survey covering 2500 sq. degrees. One of the surveys main goals is to detect galaxy clusters using Sunyaev-Zeldovich effect and use these clusters for a variety of cosmological and astrophysical studies such as the dark energy equation of state, the primordial non-gaussianity and the evolution of galaxy populations. Since 2005, we have been engaged in a comprehensive optical and near-infrared followup program (at wavelengths between 0.4 and 5 μm) to image high-significance SPT clusters, to measure their photometric redshifts, and to estimate the contamination rate of the candidate lists. These clusters are then used for various cosmological and astrophysical studies.