JKCS 041: a Coma cluster progenitor at z = 1.803
JKCS 041: a Coma cluster progenitor at z = 1.803
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DOI：
10.1051/0004-6361/201323077
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发表时间：
2013-11
影响因子：
6.5
通讯作者：
S. Andreon;A. Newman;A. Newman;G. Trinchieri;A. Raichoor;Richard S. Ellis;T. Treu
中科院分区：
文献类型：
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作者：
S. Andreon;A. Newman;A. Newman;G. Trinchieri;A. Raichoor;Richard S. Ellis;T. Treu
利用深双色近红外HST成像和无偏棱镜光谱，我们提出了一个详细的研究z = 1.803 JKCS 041星系团。我们确认，第一次为高红移集群，质量的log M 14.2太阳单位使用四种不同的技术的基础上的X射线温度，X射线光度，气体质量，和集群的丰富度。因此JKCS 041是后发座星系团这样的局部星系的前身。我们丰富的数据集和14个光谱确认的红序列星系的丰富人口使我们能够以前所未有的细节探索这个系统过去的星星形成历史。我们最感兴趣的结果是一个显著的红色序列，其恒星质量低至log M/M_∞ = 9.8，对应于2 dex的质量范围。这些静止的星系集中在星系团中心，核心半径为330千秒差距。只有很少的蓝色成员，并避免集群中心。因此，在JKCS 041中，淬火在很大程度上是在10 Gyr的回顾时间内完成的，我们可以通过对单个星系的光谱年龄测定来限制这一现象发生的时代。大多数星系在观测之前都熄灭了1.1 Gyr。质量较小的静止星系相对较年轻，对应于每质量dex的年龄减少6.5亿年，但固定质量的年龄分散仅为3.8亿年（log M/M = 11）。没有证据表明星系中有多个时期的星星形成。在JKCS 041中静止星系的大小-质量关系与我们在不确定性范围内观察到的局部星系团的大小-质量关系是一致的，并且我们在固定恒星质量下的大小增长上限为0.4 dex（95%置信度）。通过比较JKCS 041星系团和41个低红移星系团的数据，我们发现在过去的10 Gyr中，红序星系的质量函数的形式几乎没有发生变化，无论是在其暗端斜率还是特征质量方面。尽管在JKCS 041淬灭后不久就观测到了它，并且在接下来的10 Gyr中，它的质量预计会增加三倍，但它已经与现在的星团非常相似。
Using deep two-color near-infrared HST imaging and unbiased grism spectroscopy, we present a detailed study of the z = 1.803 JKCS 041 cluster. We confirm, for the first time for a high-redshift cluster, a mass of log M ≳ 14.2 in solar units using four different techniques based on the X-ray temperature, the X-ray luminosity, the gas mass, and the cluster richness. JKCS 041 is thus a progenitor of a local system like the Coma cluster. Our rich dataset and the abundant population of 14 spectroscopically confirmed red-sequence galaxies allows us to explore the past star formation history of this system in unprecedented detail. Our most interesting result is a prominent red sequence down to stellar masses as low as log M/M_⊙ = 9.8, corresponding to a mass range of 2 dex. These quiescent galaxies are concentrated around the cluster center with a core radius of 330 kpc. There are only few blue members and avoid the cluster center. In JKCS 041 quenching was therefore largely completed by a look-back time of 10 Gyr, and we can constrain the epoch at which this occurred via spectroscopic age-dating of the individual galaxies. Most galaxies were quenched about 1.1 Gyr prior to the epoch of observation. The less-massive quiescent galaxies are somewhat younger, corresponding to a decrease in age of 650 Myr per mass dex, but the scatter in age at fixed mass is only 380 Myr (at log M/M⊙ = 11). There is no evidence for multiple epochs of star formation across galaxies. The size–mass relation of quiescent galaxies in JKCS 041 is consistent with that observed for local clusters within our uncertainties, and we place an upper limit of 0.4 dex on size growth at fixed stellar mass (95% confidence). Comparing our data on JKCS 041 with 41 clusters at lower redshift, we find that the form of the mass function of red sequence galaxies has hardly evolved in the past 10 Gyr, both in terms of its faint-end slope and characteristic mass. Despite observing JKCS 041 soon after its quenching and the three-fold expected increase in mass in the next 10 Gyr, it is already remarkably similar to present-day clusters.