COSMOLOGICAL CONSTRAINTS FROM SUNYAEV–ZEL'DOVICH-SELECTED CLUSTERS WITH X-RAY OBSERVATIONS IN THE FIRST 178 deg² OF THE SOUTH POLE TELESCOPE SURVEY

Abstract

We use measurements from the South Pole Telescope (SPT) Sunyaev Zel'dovich\n(SZ) cluster survey in combination with X-ray measurements to constrain\ncosmological parameters. We present a statistical method that fits for the\nscaling relations of the SZ and X-ray cluster observables with mass while\njointly fitting for cosmology. The method is generalizable to multiple cluster\nobservables, and self-consistently accounts for the effects of the cluster\nselection and uncertainties in cluster mass calibration on the derived\ncosmological constraints. We apply this method to a data set consisting of an\nSZ-selected catalog of 18 galaxy clusters at z > 0.3 from the first 178 deg2 of\nthe 2500 deg2 SPT-SZ survey, with 14 clusters having X-ray observations from\neither Chandra or XMM. Assuming a spatially flat LCDM cosmological model, we\nfind the SPT cluster sample constrain sigma_8 (Omega_m/0.25)^0.30 = 0.785 +-\n0.037. In combination with measurements of the CMB power spectrum from the SPT\nand the seven-year WMAP data, the SPT cluster sample constrain sigma_8 = 0.795\n+- 0.016 and Omega_m = 0.255 +- 0.016, a factor of 1.5 improvement on each\nparameter over the CMB data alone. We consider several extensions beyond the\nLCDM model by including the following as free parameters: the dark energy\nequation of state (w), the sum of the neutrino masses (sum mnu), the effective\nnumber of relativistic species (Neff), and a primordial non-Gaussianity (fNL).\nWe find that adding the SPT cluster data significantly improves the constraints\non w and sum mnu beyond those found when using measurements of the CMB,\nsupernovae, baryon acoustic oscillations, and the Hubble constant. Considering\neach extension independently, we best constrain w=-0.973 +- 0.063 and the sum\nof neutrino masses sum mnu < 0.28 eV at 95% confidence, a factor of 1.25 and\n1.4 improvement, respectively, over the constraints without clusters. [abbrev.]

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Affiliated Institutions

• University of California, Berkeley US
• Harvard University US
• Argonne National Laboratory US
• Lawrence Berkeley National Laboratory US
• Space Telescope Science Institute US
• National Center for Supercomputing Applications US
• California Institute of Technology US
• Yale University US
• Excellence Cluster Universe DE
• Case Western Reserve University US
• University of California, Davis US
• Fermi National Accelerator Laboratory US
• University of Colorado Boulder US
• Ludwig-Maximilians-Universität München DE
• Millennium Institute of Astrophysics CL
• University of Missouri–Kansas City US
• University of Illinois Urbana-Champaign US
• Center for Astrophysics Harvard & Smithsonian US
• University of Chicago US
• University of Minnesota US
• Quantum Devices (United States) US
• Marshall Space Flight Center US
• Massachusetts Institute of Technology US
• University of Florida US
• University of Michigan US
• McGill University CA
• Max Planck Institute for Extraterrestrial Physics DE
• School of the Art Institute of Chicago US

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