REDSHIFTS, SAMPLE PURITY, AND BCG POSITIONS FOR THE GALAXY CLUSTER CATALOG FROM THE FIRST 720 SQUARE DEGREES OF THE SOUTH POLE TELESCOPE SURVEY
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, MI 48109 (United States)
- Department of Physics, Ludwig-Maximilians-Universitaet, Scheinerstr. 1, D-81679 Muenchen (Germany)
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
- Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)
- Department of Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States)
- Institut d'Astrophysique de Paris, UMR 7095 CNRS, Universite Pierre et Marie Curie, 98 bis boulevard Arago, F-75014 Paris (France)
- Department of Physics and Astronomy, University of Missouri, 5110 Rockhill Road, Kansas City, MO 64110 (United States)
- NIST Quantum Devices Group, 325 Broadway Mailcode 817.03, Boulder, CO 80305 (United States)
- Departamento de Astronomia y Astrosifica, Pontificia Universidad Catolica, Santiago (Chile)
- Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec H3A 2T8 (Canada)
We present the results of the ground- and space-based optical and near-infrared (NIR) follow-up of 224 galaxy cluster candidates detected with the Sunyaev-Zel'dovich (SZ) effect in the 720 deg{sup 2} of the South Pole Telescope (SPT) survey completed in the 2008 and 2009 observing seasons. We use the optical/NIR data to establish whether each candidate is associated with an overdensity of galaxies and to estimate the cluster redshift. Most photometric redshifts are derived through a combination of three different cluster redshift estimators using red-sequence galaxies, resulting in an accuracy of {Delta}z/(1 + z) = 0.017, determined through comparison with a subsample of 57 clusters for which we have spectroscopic redshifts. We successfully measure redshifts for 158 systems and present redshift lower limits for the remaining candidates. The redshift distribution of the confirmed clusters extends to z = 1.35 with a median of z{sub med} = 0.57. Approximately 18% of the sample with measured redshifts lies at z > 0.8. We estimate a lower limit to the purity of this SPT SZ-selected sample by assuming that all unconfirmed clusters are noise fluctuations in the SPT data. We show that the cumulative purity at detection significance {xi} > 5({xi} > 4.5) is {>=}95% ({>=}70%). We present the red brightest cluster galaxy (rBCG) positions for the sample and examine the offsets between the SPT candidate position and the rBCG. The radial distribution of offsets is similar to that seen in X-ray-selected cluster samples, providing no evidence that SZ-selected cluster samples include a different fraction of recent mergers from X-ray-selected cluster samples.
- OSTI ID:
- 22140064
- Journal Information:
- Astrophysical Journal, Vol. 761, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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