We present cosmological parameter constraints obtained from galaxy clusters identified by their Sunyaev-Zeldovich effect signature in the 2500 square-degree South Pole Telescope Sunyaev Zeldovich (SPT-SZ) survey. We consider the 377 cluster candidates identified at z > 0.25 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 multiwavelength 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 H0 and find σ8 = 0.784 ± 0.039 and Wm = 0.289 ± 0.042, with the parameter combination σ8 (ωm/0.27)0.3 = 0.797 ± 0.031 . 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 ?CDM, 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 (Neff ) are free parameters. When combined with constraints from the Planck CMB, H0, baryon acoustic oscillation, and SNe, adding the SPT cluster data improves the w constraint by 14%, to w = -1.023 ± 0.042.
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- cosmology: observations
- galaxies: clusters: general