COSMOLOGICAL CONSTRAINTS FROM GALAXY CLUSTERS IN THE 2500 SQUARE-DEGREE SPT-SZ SURVEY

ABSTRACT We present cosmological parameter constraints obtained from galaxy clusters identified by their Sunyaev–Zel’dovich effect signature in the 2500 square-degree South Pole Telescope Sunyaev Zel’dovich (SPT-SZ) survey. We consider the 377 cluster candidates identified at with a detection significance greater than five, corresponding to the 95% purity threshold for the survey. We compute constraints on cosmological models using the measured cluster abundance as a function of mass and redshift. We include additional constraints from multi-wavelength observations, including Chandra X-ray data for 82 clusters and a weak lensing-based prior on the normalization of the mass-observable scaling relations. Assuming a spatially flat ΛCDM cosmology, we combine the cluster data with a prior on H 0 and find and , with the parameter combination . These results are in good agreement with constraints from the cosmic microwave background (CMB) from SPT, WMAP , and Planck , as well as with constraints from other cluster data sets. We also consider several extensions to ΛCDM, including models in which the equation of state of dark energy w , the species-summed neutrino mass, and/or the effective number of relativistic species ( ) are free parameters. When combined with constraints from the Planck CMB, H 0 , baryon acoustic oscillation, and SNe, adding the SPT cluster data improves the w constraint by 14%, to .