GALAXY CLUSTERS IN FORMATION: DETERMINING THE AGE OF THE RED-SEQUENCE IN OPTICAL AND X-RAY CLUSTERS AT z ∼ 1 WITH HST 1
GALAXY CLUSTERS IN FORMATION: DETERMINING THE AGE OF THE RED-SEQUENCE IN OPTICAL AND X-RAY CLUSTERS AT z ∼ 1 WITH HST 1
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形成中的星系团：用 HST 1 确定 z 〜 1 处光学和 X 射线星系团中红序列的年龄
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
N. Suzuki
中科院分区：
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作者：
B. Koester;M. Gladders;D. Gilbank;H. Yee;K. Barbary;K. Dawson;J. Meyers;S. Perlmutter;D. Rubin;N. Suzuki
利用哈勃空间望远镜的深两波段成像，我们测量了一组主要来自红序列星系团巡天（RCS）的9个光选星系团中E/S 0星系在0.9 < z < 1.23处的色-星等关系（CMR）。我们发现在这组星系团的观测坐标系中，CMR的平均散射为0.049±0.008，而在类似的红移下，类似成像和相同分析的X射线样品中的平均散射为0.031± 0.007。CMR散射的单次爆发恒星种群模型表明，这些RCS星团中的E/S 0种群在zl <$1.6处截断了它们的恒星形成，比它们的X射线E/S 0对应物晚了大约0.9个陀螺，后者在zl <$2.1处截断。这是一个不同的演化状态的两个群体的星系团星系的表现的概念是支持的膨胀占主导地位的星系在两个样本中发现，这表明，光学选择的集群包含一个较小的部分E/S 0星系在其核心的分数的比较。主题标题：
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 RedSequence 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±0.007in 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 zl ≃ 1.6, some 0.9 Gyrs later than their X-ray E/S0 counterparts which were truncated at zl ≃ 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. Subject headings: