Galaxy Clusters in Formation: Determining the Age of the Red-Sequence in Optical and X-ray Clusters at z~1 with HST

Benjamin P. Koester; Michael D. Gladders; David G. Gilbank; H. K. C. Yee; Kyle Barbary; Kyle S. Dawson; Joshua Meyers; Saul Perlmutter; David Rubin; Nao Suzuki

arXiv · 0903.2478

Galaxy Clusters in Formation: Determining the Age of the Red-Sequence in Optical and X-ray Clusters at z~1 with HST

Benjamin P. Koester·Michael D. Gladders·David G. Gilbank·H. K. C. Yee·Kyle Barbary·Kyle S. Dawson·Joshua Meyers·Saul Perlmutter·David Rubin·Nao Suzuki

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Abstract

Using deep two-band imaging from the Hubble Space Telescope, we measure the color-magnitude relations (CMR) of E/S0 galaxies in a set of 9 optically-selected clusters principally from the Red-Sequence Cluster Survey (RCS) at 0.9 < z < 1.23. We find that the mean scatter in the CMR in the observed frame of this set of clusters is 0.049 +/- 0.008, as compared to 0.031 +/- 0.007 in a similarly imaged and identically analyzed X-ray sample at similar redshifts. Single-burst stellar population models of the CMR scatter suggest that the E/S0 population in these RCS clusters truncated their star-formation at z~1.6, some 0.9 Gyrs later than their X-ray E/S0 counterparts which were truncated at z~2.1. The notion that this is a manifestation of the differing evolutionary states of the two populations of cluster galaxies is supported by comparison of the fraction of bulge-dominated galaxies found in the two samples which shows that optically-selected clusters contain a smaller fraction of E/S0 galaxies at the their cores

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Benjamin P. Koester, Michael D. Gladders, David G. Gilbank, H. K. C. Yee, Kyle Barbary, Kyle S. Dawson, Joshua Meyers, Saul Perlmutter, David Rubin, Nao Suzuki. 2009-07-28. Galaxy Clusters in Formation: Determining the Age of the Red-Sequence in Optical and X-ray Clusters at z~1 with HST. https://arxiv.org/abs/0903.2478

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