GALAXY CLUSTERS SELECTED WITH THE SUNYAEV-ZEL'DOVICH EFFECT FROM 2008 SOUTH POLE TELESCOPE OBSERVATIONS

We present a detection-significance-limited catalog of 21 Sunyaev-Zel'dovich\nselected galaxy clusters. These clusters, along with 1 unconfirmed candidate,\nwere identified in 178 deg^2 of sky surveyed in 2008 by the South Pole\nTelescope to a depth of 18 uK-arcmin at 150 GHz. Optical imaging from the\nBlanco Cosmology Survey (BCS) and Magellan telescopes provided photometric (and\nin some cases spectroscopic) redshift estimates, with catalog redshifts ranging\nfrom z=0.15 to z>1, with a median z = 0.74. Of the 21 confirmed galaxy\nclusters, three were previously identified as Abell clusters, three were\npresented as SPT discoveries in Staniszewski et al, 2009, and three were first\nidentified in a recent analysis of BCS data by Menanteau et al, 2010; the\nremaining 12 clusters are presented for the first time in this work. Simulated\nobservations of the SPT fields predict the sample to be nearly 100% complete\nabove a mass threshold of M_200 ~ 5x10^14 M_sun/h at z = 0.6. This completeness\nthreshold pushes to lower mass with increasing redshift, dropping to ~4x10^14\nM_sun/h at z=1. The size and redshift distribution of this catalog are in good\nagreement with expectations based on our current understanding of galaxy\nclusters and cosmology. In combination with other cosmological probes, we use\nthe cluster catalog to improve estimates of cosmological parameters. Assuming a\nstandard spatially flat wCDM cosmological model, the addition of our catalog to\nthe WMAP 7-year analysis yields sigma_8 = 0.81 +- 0.09 and w = -1.07 +- 0.29, a\n~50% improvement in precision on both parameters over WMAP7 alone.

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