红色序列上暗星系团的最新发现：来自CFHTLS 119平方度的光度函数
Recent Arrival of Faint Cluster Galaxies on the Red-sequence: Luminosity Functions from 119 square degrees of CFHTLS
摘要：
自z ~ 1以来，全球恒星形成率显着下降，原因尚不清楚。红序星系在星系团中占主导地位，代表了恒星形成停止的群体，因此可能是这个问题的关键。在这项工作中，我们选择了127个丰富的星系团在0.17<z<0.36，从119平方度的加拿大-法国-夏威夷望远镜遗产巡天（CFHTLS）的光学成像数据，并构建了r '波段红序列光度函数（LF）。我们表明，LF的暗端是非常敏感的红序列星系是如何选择的，和最佳的方式来尽量减少污染的蓝色云是镜像星系的红侧的颜色-星等关系（CMR）。我们的样品的LF有一个显著的中心在Mr ~（-18.5）的突变，表明是两个种群的混合。结合我们的调查和斯隆数字巡天的低红移样本，我们发现LF的暗端没有强烈的演化（或红序矮星系与巨星之比），但从z ~ 0.2到z ~ 0，红序矮星系的相对数量增加了~3倍，这意味着在过去的2.5 Gyr中，星团红色序列的暗端有了显著的积累。
英文摘要：
The global star formation rate has decreased significantly since z ~ 1, for reasons that are not well understood. Red-sequence galaxies, dominating in galaxy clusters, represent the population that have had their star formation shut off, and may therefore be the key to this problem. In this work, we select 127 rich galaxy clusters at 0.17<z<0.36, from 119 square degrees of the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) optical imaging data, and construct the r'-band red-sequence luminosity functions (LFs). We show that the faint end of the LF is very sensitive to how red-sequence galaxies are selected, and an optimal way to minimise the contamination from the blue cloud is to mirror galaxies on the redder side of the colour-magnitude relation (CMR). The LFs of our sample have a significant inflexion centred at Mr' ~- 18.5, suggesting a mixture of two populations. Combining our survey with low redshift samples constructed from the Sloan Digital Sky Survey, we show that there is no strong evolution of the faint end of the LF (or the red-sequence dwarf-to-giant ratio) over the redshift range 0.2 < z < 0.4, but from z ~ 0.2 to z ~ 0 the relative number of red-sequence dwarf galaxies has increased by a factor of ~3, implying a significant build-up of the faint end of the cluster red-sequence over the last 2.5 Gyr.
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