B. Stalder

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.

The Optical and Near-infrared Transmission Spectrum of the Super-Earth GJ 1214b: Further Evidence for a Metal-rich Atmosphere

We present an investigation of the transmission spectrum of the 6.5 M ? planet GJ?1214b based on new ground-based observations of transits of the planet in the optical and near-infrared, and on previously published data. Observations with the VLT + FORS and Magellan + MMIRS using the technique of multi-object spectroscopy with wide slits yielded new measurements of the planets transmission spectrum from 0.61 to 0.85 ?m, and in the J, H, and K atmospheric windows. We also present a new measurement based on narrow-band photometry centered at 2.09 ?m with the VLT + HAWKI. We combined these data with results from a reanalysis of previously published FORS data from 0.78 to 1.00 ?m using an improved data reduction algorithm, and previously reported values based on Spitzer data at 3.6 and 4.5 ?m. All of the data are consistent with a featureless transmission spectrum for the planet. Our K-band data are inconsistent with the detection of spectral features at these wavelengths reported by Croll and collaborators at the level of 4.1?. The planets atmosphere must either have at least 70% H2O by mass or optically thick high-altitude clouds or haze to be consistent with the data.

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.))

STELLAR LOCUS REGRESSION: ACCURATE COLOR CALIBRATION, AND THE REAL-TIME DETERMINATION OF GALAXY CLUSTER PHOTOMETRIC REDSHIFTS

We present Stellar Locus Regression (SLR), a method of directly adjusting the instrumental broadband optical colors of stars to bring them into accord with a universal stellar color-color locus, producing accurately calibrated colors for both stars and galaxies. This is achieved without first establishing individual zeropoints for each passband, and can be performed in real-time at the telescope. We demonstrate how SLR naturally makes one wholesale correction for differences in instrumental response, for atmospheric transparency, for atmospheric extinction, and for Galactic extinction. We perform an example SLR treatment of SDSS data over a wide range of Galactic dust values and independently recover the direction and magnitude of the canonical Galactic reddening vector with 14–18 mmag RMS uncertainties. We then isolate the effect of atmospheric extinction, showing that SLR accounts for this and returns precise colors over a wide of airmass, with 5–14 mmag RMS residuals. We demonstrate that SLR-corrected colors are sufficiently accurate to allow photometric redshift estimates for galaxy clusters (using red sequence galaxies) with an uncertainty σ(z)/(1 + z) = 0.6% per cluster for redshifts 0.09 < z < 0.25. Finally, we identify our objects in the 2MASS all-sky catalog, and produce i-band zeropoints typically accurate to 18 mmag using only SLR. We offer opensource access to our IDL routines, validated and verified for the implementation of this technique, at http://stellar-locus-regression.googlecode.com. Subject headings: galaxies: fundamental parameters — methods: data analysis — stars: fundamental parameters — stars: statistics — techniques: photometric

The Redshift evolution of the mean temperature, pressure, and entropy profiles in 80 spt-selected galaxy clusters

We present the results of an X-ray analysis of 80 galaxy clusters selected in the 2500 deg^2 South Pole Telescope survey and observed with the Chandra X-ray Observatory. We divide the full sample into subsamples of ~20 clusters based on redshift and central density, performing a joint X-ray spectral fit to all clusters in a subsample simultaneously, assuming self-similarity of the temperature profile. This approach allows us to constrain the shape of the temperature profile over 0 R_(500)) regions than their low-z (0.3 < z < 0.6) counterparts. Combining the average temperature profile with measured gas density profiles from our earlier work, we infer the average pressure and entropy profiles for each subsample. Confirming earlier results from this data set, we find an absence of strong cool cores at high z, manifested in this analysis as a significantly lower observed pressure in the central 0.1R_(500) of the high-z cool-core subset of clusters compared to the low-z cool-core subset. Overall, our observed pressure profiles agree well with earlier lower-redshift measurements, suggesting minimal redshift evolution in the pressure profile outside of the core. We find no measurable redshift evolution in the entropy profile at r ≲ 0.7R_(500)—this may reflect a long-standing balance between cooling and feedback over long timescales and large physical scales. We observe a slight flattening of the entropy profile at r gsim R_(500) in our high-z subsample. This flattening is consistent with a temperature bias due to the enhanced (~3×) rate at which group-mass (~2 keV) halos, which would go undetected at our survey depth, are accreting onto the cluster at z ~ 1. This work demonstrates a powerful method for inferring spatially resolved cluster properties in the case where individual cluster signal-to-noise is low, but the number of observed clusters is high.

A MEASUREMENT OF THE CORRELATION OF GALAXY SURVEYS WITH CMB LENSING CONVERGENCE MAPS FROM THE SOUTH POLE TELESCOPE

We compare cosmic microwave background lensing convergence maps derived from South Pole Telescope (SPT) data with galaxy survey data from the Blanco Cosmology Survey, WISE, and a new large Spitzer/IRAC field designed to overlap with the SPT survey. Using optical and infrared catalogs covering between 17 and 68 deg2 of sky, we detect a correlation between the SPT convergence maps and each of the galaxy density maps at >4σ, with zero correlation robustly ruled out in all cases. The amplitude and shape of the cross-power spectra are in good agreement with theoretical expectations and the measured galaxy bias is consistent with previous work. The detections reported here utilize a small fraction of the full 2500 deg2 SPT survey data and serve as both a proof of principle of the technique and an illustration of the potential of this emerging cosmological probe.

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.

THE REST-FRAME SUBMILLIMETER SPECTRUM OF HIGH-REDSHIFT, DUSTY, STAR-FORMING GALAXIES

We present the average rest-frame spectrum of high-redshift dusty, star-forming galaxies from 250 to 770 GHz. This spectrum was constructed by stacking Atacama Large Millimeter/submillimeter Array (ALMA) 3 mm spectra of 22 such sources discovered by the South Pole Telescope and spanning z = 2.0-5.7. In addition to multiple bright spectral features of ^(12)CO, [C I], and H_2O, we also detect several faint transitions of ^(13)CO, HCN, HNC, HCO^+, and CN, and use the observed line strengths to characterize the typical properties of the interstellar medium of these high-redshift starburst galaxies. We find that the ^(13)CO brightness in these objects is comparable to that of the only other z > 2 star-forming galaxy in which ^(13)CO has been observed. We show that the emission from the high-critical density molecules HCN, HNC, HCO^+, and CN is consistent with a warm, dense medium with T_(kin) ~ 55 K and n_H_2 ≳ 10^(5.5) cm^(–3). High molecular hydrogen densities are required to reproduce the observed line ratios, and we demonstrate that alternatives to purely collisional excitation are unlikely to be significant for the bulk of these systems. We quantify the average emission from several species with no individually detected transitions, and find emission from the hydride CH and the linear molecule CCH for the first time at high redshift, indicating that these molecules may be powerful probes of interstellar chemistry in high-redshift systems. These observations represent the first constraints on many molecular species with rest-frame transitions from 0.4 to 1.2 mm in star-forming systems at high redshift, and will be invaluable in making effective use of ALMA in full science operations.