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Luminous Red Galaxy Population in Clusters at 0.2≤ z ≤0.6

Ho, Shirley and Lin, Yen-Ting and Spergel, David and Hirata, Christopher M. (2009) Luminous Red Galaxy Population in Clusters at 0.2≤ z ≤0.6. Astrophysical Journal, 697 (2). pp. 1358-1368. ISSN 0004-637X.

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We investigate statistical properties of luminous red galaxies (LRGs) in a sample of X-ray-selected galaxy clusters at intermediate redshift (0.2 ≤ z ≤ 0.6) of mass range from ~1 × 10^(14) M_☉ to ~8 × 10^(14) M_☉ . The LRGs are selected based on carefully designed color criteria, and the cluster membership is assessed via photometric redshifts. As clusters and LRGs are both viewed as promising tracer of the underlying dark matter distribution, understanding the distribution of LRGs within clusters is an important issue. Our main findings include (1) the halo occupation distribution (HOD) of LRGs inside our cluster sample is N(M) = k(M/10^(14) h^(–1) M_☉)^a , where a = 0.495 ± 0.105 and k = 1.455 ± 0.285 assuming a Poisson distribution for N(M). If we assume the form of N(M) = 1 + k(M/10^(14) h^(–1)M_☉) a , where a = 0.580 ± 0.130 and k = 0.975 ± 0.240 assuming a Poisson distribution for N(M). (2) The HOD of LRGs [N(M)] and the satellite distribution of LRGs [N(M) – 1] are both consistent with being Poisson. To be more quantitative, we find Var(N)/N = 1.43 ± 0.35 and Var(N – 1)/(N – 1) = 1.82 ± 0.50. (3) The radial profile of LRGs within clusters when fitted with a Navarro-Frenk-White profile gives a concentration of 17.5^(+7.1)_(–4.3) (6.0^(+3.2)_(–1.9)) including (excluding) brightest LRGs (BLRGs). In essence, the BLRGs are more concentrated toward the center of the clusters than the other LRGs in clusters. We also discuss the implications of these observations on the evolution of massive galaxies in clusters.

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Additional Information:© 2009. The American Astronomical Society. Received 2007 October 16; accepted 2009 March 5; published 2009 May 12. We thank Nikhil Padmanabhan, Charlie Conroy, Rachel Mandelbaum, Scott Tremaine, Jim Gunn, Jerry Ostriker, Zheng Zheng, and Thomas Reiprich for helpful discussions, and R. Burenin and A. Vikhlinin for help with the selection function of the 400d survey. Y.-T.L. acknowledges support from the Princeton-Catolica Fellowship, NSF PIRE grant OISE- 0530095, and FONDAP-Andes. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the US Department of Energy, the National Aeronautics and Space Administration, the JapaneseMonbukagakusho, theMax Planck Society, and the Higher Education Funding Council for England. The SDSS Web site is The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions. The Participating Institutions are the American Museum of Natural History, Astrophysical Institute Potsdam, University of Basel, University of Cambridge, Case Western Reserve University, University of Chicago, Drexel University, Fermilab, the Institute for Advanced Study, the Japan Participation Group, Johns Hopkins University, the Joint Institute for Nuclear Astrophysics, the Kavli Institute for Particle Astrophysics and Cosmology, the Korean Scientist Group, the Chinese Academy of Sciences (LAMOST), Los Alamos National Laboratory, theMax-Planck- Institute for Astronomy (MPIA), the Max-Planck-Institute for Astrophysics (MPA), New Mexico State University, Ohio State University, University of Pittsburgh, University of Portsmouth, Princeton University, the United States Naval Observatory, and the University of Washington.
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Princeton-Catolica FellowshipUNSPECIFIED
Partnerships for International Research and Education (National Science Foundation)OISE-0530095
Subject Keywords:cosmology: observations; galaxies: clusters: general; galaxies: formation
Record Number:CaltechAUTHORS:20090831-103007352
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Official Citation:Luminous Red Galaxy Population in Clusters at 0.2≤ z ≤0.6 Shirley Ho, Yen-Ting Lin, David Spergel, and Christopher M. Hirata 2009 ApJ 697 1358-1368 doi: 10.1088/0004-637X/697/2/1358
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:15481
Deposited By: Ruth Sustaita
Deposited On:11 Sep 2009 22:20
Last Modified:26 Dec 2012 11:17

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