Browsing by Author "Carlstrom, J. E."

Now showing 1 - 9 of 9
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    Cluster Cosmology Constraints from the 2500 deg2 SPT-SZ Survey: Inclusion of Weak Gravitational Lensing Data from Magellan and the Hubble Space Telescope
    (2019) Bocquet, S.; Dietrich, J. P.; Schrabback, T.; Bleem, L. E.; Klein, M.; Allen, S. W.; Applegate, D. E.; Ashby, M. L. N.; Bautz, M.; Bayliss, M.; Benson, B. A.; Brodwin, M.; Bulbul, E.; Canning, R. E. A.; Capasso, R.; Carlstrom, J. E.; Chang, C. L.; Chiu, I; Cho, H-M; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Desai, S.; Dobbs, M. A.; Foley, R. J.; Forman, W. R.; Garmire, G. P.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Grandis, S.; Gupta, N.; Halverson, N. W.; Hlavacek-Larrondo, J.; Hoekstra, H.; Holder, G. P.; Holzapfel, W. L.; Hou, Z.; Hrubes, J. D.; Huang, N.; Jones, C.; Khullar, G.; Knox, L.; Kraft, R.; Lee, A. T.; von der Linden, A.; Luong-Van, D.; Mantz, A.; Marrone, D. P.; McDonald, M.; McMahon, J. J.; Meyer, S. S.; Mocanu, L. M.; Mohr, J. J.; Morris, R. G.; Padin, S.; Patil, S.; Pryke, C.; Rapetti, D.; Reichardt, C. L.; Rest, A.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Shirokoff, E.; Stalder, B.; Stanford, S. A.; Staniszewski, Z.; Stark, A. A.; Story, K. T.; Strazzullo, V; Stubbs, C. W.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zenteno, A.
    We derive cosmological constraints using a galaxy cluster sample selected from the 2500 deg(2) SPT-SZ survey. The sample spans the redshift range 0.25 < z < 1.75 and contains 343 clusters with SZ detection significance xi > 5. The sample is supplemented with optical weak gravitational lensing measurements of 32 clusters with 0.29 < z < 1.13 (from Magellan and Hubble Space Telescope) and X-ray measurements of 89 clusters with 0.25 < z < 1.75 (from Chandra). We rely on minimal modeling assumptions: (i) weak lensing provides an accurate means of measuring halo masses, (ii) the mean SZ and X-ray observables are related to the true halo mass through power-law relations in mass and dimensionless Hubble parameter E(z) with a priori unknown parameters, and (iii) there is (correlated, lognormal) intrinsic scatter and measurement noise relating these observables to their mean relations. We simultaneously fit for these astrophysical modeling parameters and for cosmology. Assuming a flat nu Lambda CDM model, in which the sum of neutrino masses is a free parameter, we measure Omega(m) = 0.276 +/- 0.047, sigma(8) = 0.781 +/- 0.037, and sigma(8)(Omega(m)/0.3)(0.2) = 0.766 +/- 0.025. The redshift evolutions of the X-ray Y-X-mass and M-gas-mass relations are both consistent with self-similar evolution to within 1 sigma. The mass slope of the Y-X-mass relation shows a 2.3 sigma deviation from self-similarity. Similarly, the mass slope of the M-gas-mass relation is steeper than self-similarity at the 2.5 sigma level. In a nu omega CDM cosmology, we measure the dark energy equation-of-state parameter w = -1.55 +/- 0.41 from the cluster data. We perform a measurement of the growth of structure since redshift z similar to 1.7 and find no evidence for tension with the prediction from general relativity. This is the first analysis of the SPT cluster sample that uses direct weak-lensing mass calibration and is a step toward using the much larger weak-lensing data set from DES. We provide updated redshift and mass estimates for the SPT sample.
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    COSMOLOGICAL CONSTRAINTS FROM SUNYAEV-ZEL'DOVICH-SELECTED CLUSTERS WITH X-RAY OBSERVATIONS IN THE FIRST 178 deg2 OF THE SOUTH POLE TELESCOPE SURVEY
    (2013) Benson, B. A.; de Haan, T.; Dudley, J. P.; Reichardt, C. L.; Aird, K. A.; Andersson, K.; Armstrong, R.; Ashby, M. L. N.; Bautz, M.; Bayliss, M.; Bazin, G.; Bleem, L. E.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Cho, H. M.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; Desai, S.; Dobbs, M. A.; Foley, R. J.; Forman, W. R.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; Harrington, N.; High, F. W.; Holder, G. P.; Holzapfel, W. L.; Hoover, S.; Hrubes, J. D.; Jones, C.; Joy, M.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Liu, J.; Lueker, M.; Luong-Van, D.; Mantz, A.; Marrone, D. P.; McDonald, M.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Mocanu, L.; Mohr, J. J.; Montroy, T. E.; Murray, S. S.; Natoli, T.; Padin, S.; Plagge, T.; Pryke, C.; Rest, A.; Ruel, J.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Shaw, L.; Shirokoff, E.; Song, J.; Spieler, H. G.; Stalder, B.; Staniszewski, Z.; Stark, A. A.; Story, K.; Stubbs, C. W.; Suhada, R.; van Engelen, A.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zahn, O.; Zenteno, A.
    We usemeasurements from the South Pole Telescope (SPT) Sunyaev-Zel'dovich (SZ) cluster survey in combination with X-ray measurements to constrain cosmological parameters. We present a statistical method that fits for the scaling relations of the SZ and X-ray cluster observables with mass while jointly fitting for cosmology. The method is generalizable to multiple cluster observables, and self-consistently accounts for the effects of the cluster selection and uncertainties in cluster mass calibration on the derived cosmological constraints. We apply this method to a data set consisting of an SZ-selected catalog of 18 galaxy clusters at z > 0.3 from the first 178 deg(2) of the 2500 deg(2) SPT-SZ survey, with 14 clusters having X-ray observations from either Chandra or XMM-Newton. Assuming a spatially flat Lambda CDM cosmological model, we find the SPT cluster sample constrains sigma(8)(Omega(m)/0.25)(0.30) = 0.785 +/- 0.037. In combination with measurements of the cosmic microwave background (CMB) power spectrum from the SPT and the seven-year Wilkinson Microwave Anisotropy Probe data, the SPT cluster sample constrains sigma(8) = 0.795 +/- 0.016 and Omega(m) = 0.255 +/- 0.016, a factor of 1.5 improvement on each parameter over the CMB data alone. We consider several extensions beyond the Lambda CDM model by including the following as free parameters: the dark energy equation of state (w), the sum of the neutrino masses (Sigma m(nu)), the effective number of relativistic species (N-eff), and a primordial non-Gaussianity (f(NL)). We find that adding the SPT cluster data significantly improves the constraints on w and Sigma m(nu) beyond those found when using measurements of the CMB, supernovae, baryon acoustic oscillations, and the Hubble constant. Considering each extension independently, we best constrain w = -0.973 +/- 0.063 and the sum of neutrino masses Sigma m(nu) < 0.28 eV at 95% confidence, a factor of 1.25 and 1.4 improvement, respectively, over the constraints without clusters. Assuming a Lambda CDM model with a free N-eff and Sigma m(nu), we measure N-eff = 3.91 +/- 0.42 and constrain Sigma m(nu) < 0.63 eV at 95% confidence. We also use the SPT cluster sample to constrain f(NL) = -220 +/- 317, consistent with zero primordial non-Gaussianity. Finally, we discuss the current systematic limitations due to the cluster mass calibration, and future improvements for the recently completed 2500 deg(2) SPT-SZ survey. The survey has detected similar to 500 clusters with a median redshift of similar to 0.5 and a median mass of similar to 2.3 x 10(14) M-circle dot h(-1) and, when combined with an improved cluster mass calibration and existing external cosmological data sets will significantly improve constraints on w.
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    DISCOVERY AND COSMOLOGICAL IMPLICATIONS OF SPT-CL J2106-5844, THE MOST MASSIVE KNOWN CLUSTER AT z > 1
    (2011) Foley, R. J.; Andersson, K.; Bazin, G.; de Haan, T.; Ruel, J.; Ade, P. A. R.; Aird, K. A.; Armstrong, R.; Ashby, M. L. N.; Bautz, M.; Benson, B. A.; Bleem, L. E.; Bonamente, M.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; Desai, S.; Dobbs, M. A.; Dudley, J. P.; Fazio, G. G.; Forman, W. R.; Garmire, G.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; High, F. W.; Holder, G. P.; Holzapfel, W. L.; Hoover, S.; Hrubes, J. D.; Jones, C.; Joy, M.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Lueker, M.; Luong-Van, D.; Marrone, D. P.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Mohr, J. J.; Montroy, T. E.; Murray, S. S.; Padin, S.; Plagge, T.; Pryke, C.; Reichardt, C. L.; Rest, A.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Schaffer, K. K.; Shaw, L.; Shirokoff, E.; Song, J.; Spieler, H. G.; Stalder, B.; Stanford, S. A.; Staniszewski, Z.; Stark, A. A.; Story, K.; Stubbs, C. W.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zenteno, A.
    Using the South Pole Telescope (SPT), we have discovered the most massive known galaxy cluster at z > 1, SPT-CL J2106-5844. In addition to producing a strong Sunyaev-Zel'dovich (SZ) effect signal, this system is a luminous X-ray source and its numerous constituent galaxies display spatial and color clustering, all indicating the presence of a massive galaxy cluster. Very Large Telescope and Magellan spectroscopy of 18 member galaxies shows that the cluster is at z = 1.132(-0.003)(+0.002). Chandra observations obtained through a combined HRC-ACIS GTO program reveal an X-ray spectrum with an Fe K line redshifted by z = 1.18 +/- 0.03. These redshifts are consistent with the galaxy colors found in optical, near-infrared, and mid-infrared imaging. SPT-CL J2106-5844 displays extreme X-ray properties for a cluster having a core-excluded temperature of T-X = 11.0(-1.9)(+2.6) keV and a luminosity (within r(500)) of L-X(0.5-2.0 keV) = (13.9 +/- 1.0) x 10(44) erg s(-1). The combined mass estimate from measurements of the SZ effect and X-ray data is M-200 = (1.27 +/- 0.21) x 10(15) h(70)(-1) M-circle dot. The discovery of such amassive gravitationally collapsed system at high redshift provides an interesting laboratory for galaxy formation and evolution, and is a probe of extreme perturbations of the primordial matter density field. We discuss the latter, determining that, under the assumption of Lambda CDM cosmology with only Gaussian perturbations, there is only a 7% chance of finding a galaxy cluster similar to SPT-CL J2106-5844 in the 2500 deg(2) SPT survey region and that only one such galaxy cluster is expected in the entire sky.
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    Galaxy clusters discovered via the sunyaev-Zel'dovich effect in the 2500-square-degree SPT-SZ survey
    (2015) Bleem, L. E.; Stalder, B.; de Haan, T.; Aird, K. A.; Allen, S. W.; Applegate, D. E.; Ashby, M. L. N; Bautz, M.; Bayliss, M.; Clocchiatti, Alejandro; Benson, B. A.; Bocquet, S.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Chiu, I.; Cho, H. M.; Crawford, T. M.; Crites, A. T.; Desai, S.
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    GALAXY CLUSTERS DISCOVERED VIA THE SUNYAEV-ZEL'DOVICH EFFECT IN THE FIRST 720 SQUARE DEGREES OF THE SOUTH POLE TELESCOPE SURVEY
    (2013) Reichardt, C. L.; Stalder, B.; Bleem, L. E.; Montroy, T. E.; Aird, K. A.; Andersson, K.; Armstrong, R.; Ashby, M. L. N.; Bautz, M.; Bayliss, M.; Bazin, G.; Benson, B. A.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Cho, H. M.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Desai, S.; Dobbs, M. A.; Dudley, J. P.; Foley, R. J.; Forman, W. R.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; Harrington, N. L.; High, F. W.; Holder, G. P.; Holzapfel, W. L.; Hoover, S.; Hrubes, J. D.; Jones, C.; Joy, M.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Liu, J.; Lueker, M.; Luong-Van, D.; Mantz, A.; Marrone, D. P.; McDonald, M.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Mocanu, L.; Mohr, J. J.; Murray, S. S.; Natoli, T.; Padin, S.; Plagge, T.; Pryke, C.; Rest, A.; Ruel, J.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Shaw, L.; Shirokoff, E.; Song, J.; Spieler, H. G.; Staniszewski, Z.; Stark, A. A.; Story, K.; Stubbs, C. W.; Suhada, R.; van Engelen, A.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zahn, O.; Zenteno, A.
    We present a catalog of galaxy cluster candidates, selected through their Sunyaev-Zel'dovich (SZ) effect signature in the first 720 deg(2) of the South Pole Telescope (SPT) survey. This area was mapped with the SPT in the 2008 and 2009 austral winters to a depth of similar to 18 mu K-CMB-arcmin at 150 GHz; 550 deg(2) of it was also mapped to similar to 44 mu K-CMB-arcmin at 95 GHz. Based on optical imaging of all 224 candidates and near-infrared imaging of the majority of candidates, we have found optical and/or infrared counterparts for 158, which we then classify as confirmed galaxy clusters. Of these 158 clusters, 135 were first identified as clusters in SPT data, including 117 new discoveries reported in this work. This catalog triples the number of confirmed galaxy clusters discovered through the SZ effect. We report photometrically derived (and in some cases spectroscopic) redshifts for confirmed clusters and redshift lower limits for the remaining candidates. The catalog extends to high redshift with a median redshift of z = 0.55 and maximum confirmed redshift of z = 1.37. Forty-five of the clusters have counterparts in the ROSAT bright or faint source catalogs from which we estimate X-ray fluxes. Based on simulations, we expect the catalog to be nearly 100% complete above M-500 approximate to 5 x 10(14) M-circle dot h(70)(-1) at z greater than or similar to 0.6. There are 121 candidates detected at signal-to-noise ratio greater than five, at which the catalog purity is measured to be 95%. From this high-purity subsample, we exclude the z < 0.3 clusters and use the remaining 100 candidates to improve cosmological constraints following the method presented by Benson et al. Adding the cluster data to CMB + BAO + H-0 data leads to a preference for non-zero neutrino masses while only slightly reducing the upper limit on the sum of neutrino masses to Sigma m(nu) < 0.38 eV (95% CL). For a spatially flat wCDM cosmological model, the addition of this catalog to the CMB + BAO + H-0 + SNe results yields sigma(8) = 0.807 +/- 0.027 and w = -1.010 +/- 0.058, improving the constraints on these parameters by a factor of 1.4 and 1.3, respectively. The larger cluster catalog presented in this work leads to slight improvements in cosmological constraints from those presented by Benson et al. These cosmological constraints are currently limited by uncertainty in the cluster mass calibration, not the size or quality of the cluster catalog. A multi-wavelength observation program to improve the cluster mass calibration will make it possible to realize the full potential of the final 2500 deg(2) SPT cluster catalog to constrain cosmology.
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    SOUTH POLE TELESCOPE DETECTIONS OF THE PREVIOUSLY UNCONFIRMED PLANCK EARLY SUNYAEV-ZEL'DOVICH CLUSTERS IN THE SOUTHERN HEMISPHERE
    (2011) Story, K.; Aird, K. A.; Andersson, K.; Armstrong, R.; Bazin, G.; Benson, B. A.; Bleem, L. E.; Bonamente, M.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Desai, S.; Dobbs, M. A.; Dudley, J. P.; Foley, R. J.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; High, F. W.; Holder, G. P.; Holzapfel, W. L.; Hoover, S.; Hrubes, J. D.; Joy, M.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Lueker, M.; Luong-Van, D.; Marrone, D. P.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Mohr, J. J.; Montroy, T. E.; Padin, S.; Plagge, T.; Pryke, C.; Reichardt, C. L.; Rest, A.; Ruel, J.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Schaffer, K. K.; Shaw, L.; Shirokoff, E.; Song, J.; Spieler, H. G.; Stalder, B.; Staniszewski, Z.; Stark, A. A.; Stubbs, C. W.; Vanderlinde, K.; Vieira, J. D.; Williamson, R.; Zenteno, A.
    We present South Pole Telescope (SPT) observations of the five galaxy cluster candidates in the southern hemisphere which were reported as unconfirmed in the Planck Early Sunyaev-Zel'dovich (ESZ) sample. One cluster candidate, PLCKESZ G255.62-46.16, is located in the 2500 deg(2) SPT SZ survey region and was reported previously as SPT-CL J0411-4819. For the remaining four candidates, which are located outside of the SPT SZ survey region, we performed short, dedicated SPT observations. Each of these four candidates was strongly detected in maps made from these observations, with signal-to-noise ratios ranging from 6.3 to 13.8. We have observed these four candidates on theMagellan-Baade telescope and used these data to estimate cluster redshifts from the red sequence. Resulting redshifts range from 0.24 to 0.46. We report measurements of Y-0'.75, the integrated Comptonization within a 0'.75 radius, for all five candidates. We also report X-ray luminosities calculated from ROSAT All-Sky Survey catalog counts, as well as optical and improved SZ coordinates for each candidate. The combination of SPT SZ measurements, optical red-sequence measurements, and X-ray luminosity estimates demonstrates that these five Planck ESZ cluster candidates do indeed correspond to real galaxy clusters with redshifts and observable properties consistent with the rest of the ESZ sample.
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    SPT 0538-50: PHYSICAL CONDITIONS IN THE INTERSTELLAR MEDIUM OF A STRONGLY LENSED DUSTY STAR-FORMING GALAXY AT z=2.8
    (2013) Bothwell, M. S.; Aguirre, J. E.; Chapman, S. C.; Marrone, D. P.; Vieira, J. D.; Ashby, M. L. N.; Aravena, M.; Benson, B. A.; Bock, J. J.; Bradford, C. M.; Brodwin, M.; Carlstrom, J. E.; Crawford, T. M.; De Breuck, C.; Downes, T. P.; Fassnacht, C. D.; Gonzalez, A. H.; Greve, T. R.; Gullberg, B.; Hezaveh, Y.; Holder, G. P.; Holzapfel, W. L.; Ibar, E.; Ivison, R.; Kamenetzky, J.; Keisler, R.; Lupu, R. E.; Ma, J.; Malkan, M.; McIntyre, V.; Murphy, E. J.; Nguyen, H. T.; Reichardt, C. L.; Rosenman, M.; Spilker, J. S.; Stalder, B.; Stark, A. A.; Strandet, M.; Vernet, J.; Weiss, A.; Welikala, N.
    We present observations of SPT-S J053816-5030.8, a gravitationally lensed dusty star-forming galaxy (DSFG) at z = 2.7817 that was first discovered at millimeter wavelengths by the South Pole Telescope. SPT 0538-50 is typical of the brightest sources found by wide-field millimeter-wavelength surveys, being lensed by an intervening galaxy at moderate redshift (in this instance, at z = 0.441). We present a wide array of multi-wavelength spectroscopic and photometric data on SPT 0538-50, including data from ALMA, Herschel PACS and SPIRE, Hubble, Spitzer, the Very Large Telescope, ATCA, APEX, and the Submillimeter Array. We use high-resolution imaging from the Hubble Space Telescope to de-blend SPT 0538-50, separating DSFG emission from that of the foreground lens. Combined with a source model derived from ALMA imaging (which suggests a magnification factor of 21+/-4), we derive the intrinsic properties of SPT 0538-50, including the stellar mass, far-IR luminosity, star formation rate, molecular gas mass, and-using molecular line fluxes-the excitation conditions within the interstellar medium. The derived physical properties argue that we arewitnessing compact, merger-driven star formation in SPT 0538-50 similar to local starburst galaxies and unlike that seen in some other DSFGs at this epoch.
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    SPT-CL J0205-5829: A z=1.32 EVOLVED MASSIVE GALAXY CLUSTER IN THE SOUTH POLE TELESCOPE SUNYAEV-ZEL'DOVICH EFFECT SURVEY
    (2013) Stalder, B.; Ruel, J.; Suhada, R.; Brodwin, M.; Aird, K. A.; Andersson, K.; Armstrong, R.; Ashby, M. L. N.; Bautz, M.; Bayliss, M.; Bazin, G.; Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Cho, H. M.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Desai, S.; Dobbs, M. A.; Dudley, J. P.; Foley, R. J.; Forman, W. R.; George, E. M.; Gettings, D.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; Harrington, N. L.; High, F. W.; Holder, G. P.; Holzapfel, W. L.; Hoover, S.; Hrubes, J. D.; Jones, C.; Joy, M.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Liu, J.; Lueker, M.; Luong-Van, D.; Mantz, A.; Marrone, D. P.; McDonald, M.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Mocanu, L.; Mohr, J. J.; Montroy, T. E.; Murray, S. S.; Natoli, T.; Nurgaliev, D.; Padin, S.; Plagge, T.; Pryke, C.; Reichardt, C. L.; Rest, A.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Shaw, L.; Shirokoff, E.; Song, J.; Spieler, H. G.; Stanford, S. A.; Staniszewski, Z.; Stark, A. A.; Story, K.; Stubbs, C. W.; van Engelen, A.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zahn, O.; Zenteno, A.
    The galaxy cluster SPT-CL J0205-5829 currently has the highest spectroscopically confirmed redshift, z = 1.322, in the South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) survey. XMM-Newton observations measure a core-excluded temperature of T-X = 8.7(-0.8)(+1.0) keV producing a mass estimate that is consistent with the Sunyaev-Zel'dovich-derived mass. The combined SZ and X-ray mass estimate of M-500 = (4.8+/-0.8) x 10(14)h(70)(-1) M-circle dot makes it the most massive known SZ-selected galaxy cluster at z > 1.2 and the second most massive at z > 1. Using optical and infrared observations, we find that the brightest galaxies in SPT-CL J0205-5829 are already well evolved by the time the universe was < 5 Gyr old, with stellar population ages greater than or similar to 3 Gyr, and low rates of star formation (< 0.5 M-circle dot yr(-1)). We find that, despite the high redshift and mass, the existence of SPT-CL J0205-5829 is not surprising given a flat Lambda CDM cosmology with Gaussian initial perturbations. The a priori chance of finding a cluster of similar rarity (or rarer) in a survey the size of the 2500 deg(2) SPT-SZ survey is 69%.
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    Sub-kiloparsec imaging of cool molecular gas in two strongly lensed dusty
    (2015) Spilker, J. S.; Aravena, M.; Marrone, D. P.; Bethermin, M.; Bothwell, M. S.; Carlstrom, J. E.; Chapman, S. C.; Collier, J. D.; De Breuck, C.; González López, Jorge