Mehrtens, Nicola and Romer, A. Kathy and Nichol, Robert C. and Collins, Chris A. and Sahlen, Martin and Rooney, Philip J. and Mayers, Julian A. and Bermeo-Hernandez, A. and Bristow, Martyn and Capozzi, Diego and Christodoulou, L. and Comparat, Johan and Hilton, Matt and Hoyle, Ben and Kay, Scott T. and Liddle, Andrew R. and Mann, Robert G. and Masters, Karen and Miller, Christopher J. and Parejko, John K. and Prada, Francisco and Ross, Ashley J. and Schneider, Donald P. and Stott, John P. and Streblyanska, Alina and Viana, Pedro T. P. and White, Martin and Wilcox, Harry and Zehavi, Idit (2016) The XMM Cluster Survey:the halo occupation number of BOSS galaxies in X-ray clusters. Monthly Notices of the Royal Astronomical Society, 463 (2). pp. 1929-1943. ISSN 0035-8711
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Abstract
We present a direct measurement of the mean halo occupation distribution (HOD) of galaxies taken from the eleventh data release (DR11) of the Sloan Digital Sky Survey-III Baryon Oscillation Spectroscopic Survey (BOSS). The HOD of BOSS low-redshift (LOWZ: 0.2 <z <0.4) and Constant-Mass (CMASS: 0.43 <z <0.7) galaxies is inferred via their association with the dark matter haloes of 174 X-ray-selected galaxy clusters drawn from the XMM Cluster Survey (XCS). Halo masses are determined for each galaxy cluster based on X-ray temperature measurements, and range between log(10)(M-180/M-circle dot) = 13 and 15. Our directly measured HODs are consistent with the HOD-model fits inferred via the galaxy-clustering analyses of Parejko et al. for the BOSS LOWZ sample and White et al. for the BOSS CMASS sample. Under the simplifying assumption that the other parameters that describe the HOD hold the values measured by these authors, we have determined a best-fitting alpha-index of 0.91 +/- 0.08 and 1.27(-0.04)(+0.03) for the CMASS and LOWZ HOD, respectively. These alpha-index values are consistent with those measured by White et al. and Parejko et al. In summary, our study provides independent support for the HOD models assumed during the development of the BOSS mock-galaxy catalogues that have subsequently been used to derive BOSS cosmological constraints.