An Increase in the Faint Red Galaxy Population in Massive Clusters since z ~ 0.5
An Increase in the Faint Red Galaxy Population in Massive Clusters since z ~ 0.5
复制标题
DOI：
10.1086/514329
复制
发表时间：
2007-03
期刊：
影响因子：
--
通讯作者：
J. Stott;I. Smail;A. Edge;H. Ebeling;Graham P. Smith;J. Kneib;K. Pimbblet
中科院分区：
文献类型：
--
作者：
J. Stott;I. Smail;A. Edge;H. Ebeling;Graham P. Smith;J. Kneib;K. Pimbblet
我们比较了红色星系的光度函数躺在休息框架（U-V）色星等序列中的均匀样本的10个X射线发光的星系团从MACS调查在z ~ 0.5，以类似的选择X射线星系团样本在z ~ 0.1。我们利用深哈勃太空望远镜ACS成像的F555 W和F814 W通带的中央1.2兆秒差距直径区域的遥远的星系团测量精确的颜色在这些地区的星系和统计校正的污染场星系使用观测的空白领域。我们应用一个相同的分析，以地面测光的z ~ 0.1的样品。这一比较表明，在z ~ 0.5和z ~ 0.1之间的4 Gyr期间，相对于在大质量星系团中心区域看到的明亮星系群，暗淡的MV ~-19红色星系的数量大约翻了一番。我们通过测量红序上的矮星-巨星比来量化这种差异，因为z ~ 0.5，它至少增加了2.2 ± 0.4倍。这与在高密度环境中的许多暗淡的蓝色恒星形成星系在哈勃时间的后半部分转变为红色序列的想法一致。
We compare the luminosity functions for red galaxies lying on the rest-frame (U - V) color-magnitude sequence in a homogeneous sample of 10 X-ray-luminous clusters from the MACS survey at z ~ 0.5 to a similarly selected X-ray cluster sample at z ~ 0.1. We exploit deep Hubble Space Telescope ACS imaging in the F555W and F814W passbands of the central 1.2 Mpc diameter regions of the distant clusters to measure precise colors for the galaxies in these regions and statistically correct for contamination by field galaxies using observations of blank fields. We apply an identical analysis to ground-based photometry of the z ~ 0.1 sample. This comparison demonstrates that the number of faint, MV ~ -19, red galaxies relative to the bright population seen in the central regions of massive clusters has roughly doubled over the 4 Gyr between z ~ 0.5 and z ~ 0.1. We quantify this difference by measuring the dwarf-giant ratio on the red sequence, which increases by a factor of at least 2.2 ± 0.4 since z ~ 0.5. This is consistent with the idea that many faint, blue, star-forming galaxies in high-density environments are transforming onto the red sequence in the last half of the Hubble time.