Redshifts, sample purity, and BCG positions for the galaxy cluster catalog from the first 720 square degrees of the south pole telescope survey

J. Song, A. Zenteno, B. Stalder, S. Desai, L. E. Bleem, K. A. Aird, R. Armstrong, M. L.N. Ashby, M. Bayliss, G. Bazin, B. A. Benson, E. Bertin, M. Brodwin, J. E. Carlstrom, C. L. Chang, H. M. Cho, A. Clocchiatti, T. M. Crawford, A. T. Crites, T. De HaanM. A. Dobbs, J. P. Dudley, R. J. Foley, E. M. George, D. Gettings, M. D. Gladders, A. H. Gonzalez, N. W. Halverson, N. L. Harrington, F. W. High, G. P. Holder, W. L. Holzapfel, S. Hoover, J. D. Hrubes, M. Joy, R. Keisler, L. Knox, A. T. Lee, E. M. Leitch, J. Liu, M. Lueker, D. Luong-Van, D. P. Marrone, M. McDonald, J. J. McMahon, J. Mehl, S. S. Meyer, L. Mocanu, J. J. Mohr, T. E. Montroy, T. Natoli, D. Nurgaliev, S. Padin, T. Plagge, C. Pryke, C. L. Reichardt, A. Rest, J. Ruel, J. E. Ruhl, B. R. Saliwanchik, A. Saro, J. T. Sayre, K. K. Schaffer, L. Shaw, E. Shirokoff, R. Šuhada, H. G. Spieler, S. A. Stanford, Z. Staniszewski, A. A. Stark, K. Story, C. W. Stubbs, A. Van Engelen, K. Vanderlinde, J. D. Vieira, R. Williamson, O. Zahn

Research output: Contribution to journalArticle

70 Scopus citations

Abstract

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 deg2 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 Δz/(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 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 ξ > 5(ξ > 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.

Original languageEnglish (US)
Article number22
JournalAstrophysical Journal
Volume761
Issue number1
DOIs
StatePublished - Dec 10 2012

Keywords

  • cosmology: observations
  • galaxies: clusters: general
  • galaxies: distances and redshifts

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Fingerprint Dive into the research topics of 'Redshifts, sample purity, and BCG positions for the galaxy cluster catalog from the first 720 square degrees of the south pole telescope survey'. Together they form a unique fingerprint.

  • Cite this

    Song, J., Zenteno, A., Stalder, B., Desai, S., Bleem, L. E., Aird, K. A., Armstrong, R., Ashby, M. L. N., Bayliss, M., Bazin, G., Benson, B. A., Bertin, E., Brodwin, M., Carlstrom, J. E., Chang, C. L., Cho, H. M., Clocchiatti, A., Crawford, T. M., Crites, A. T., ... Zahn, O. (2012). Redshifts, sample purity, and BCG positions for the galaxy cluster catalog from the first 720 square degrees of the south pole telescope survey. Astrophysical Journal, 761(1), [22]. https://doi.org/10.1088/0004-637X/761/1/22