arXiv 1203.35412012-03astro-ph.CO

矮人和巨人的故事：使用z=1.62的集群来了解红色序列在过去95亿年中的增长

A Tale of Dwarfs and Giants: Using a z=1.62 Cluster to Understand How the Red Sequence Grew Over The Last 9.5 Billion Years

Gregory H. Rudnick, Kim-Vy Tran, Casey Papovich, Ivelina Momcheva, Christopher Willmer

备注：: 15 pages, 7 figures, accepted for publication in the Astrophysical Journal. With respect to previous version, the likely descendants of the z=1.62 cluster now have a more modest mass and the required luminosity growth on the red sequence is slightly lower. No major conclusions have changed
DOI：: 10.1088/0004-637X/755/1/14

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摘要：

我们研究的红色序列的星系团在z=1.62，并遵循其演变的干预9.5 Gyr到今天。使用深YJK成像与HAWK-I仪器上的VLT，我们确定了一个紧密的红色序列，并构建其休息帧i波段光度函数（LF）。在这个星系团中有一个明显的暗红色星系的缺陷，这导致了LF的周转。我们将红色序列LF与z<0.8的星系团进行了比较，校正了被动演化的光度。在z=1.62和z=0.6之间，红色星团序列LF的形状没有演变，但在z<0.6时，微弱的星群显著增加。同时，在z=1.62至0.6之间，红色序列上的推断的总光增长约2倍，并且LF的亮端变得更密集。我们构建了一个简单的红色序列演化模型，该模型在总光度中增长红色序列，并在z>0.6时匹配恒定的LF形状。在这个模型中，星系团从磁场中吸积蓝色星系，然后熄灭，随后允许合并。我们发现在z=1.62和z=0.6之间的4 Gyr期间，星系团之间的3- 4合并与观测到的两个红移之间的光度函数演化相匹配。推断的合并率与该集群的其他研究一致。我们的研究结果支持了这样一种观点，即星系合并在大质量星系团的主要生长阶段是在所有光度下形成红色序列人口的一个重要过程。

英文摘要：

We study the red sequence in a cluster of galaxies at z=1.62 and follow its evolution over the intervening 9.5 Gyr to the present day. Using deep YJKs imaging with the HAWK-I instrument on the VLT we identify a tight red sequence and construct its rest-frame i-band luminosity function (LF). There is a marked deficit of faint red galaxies in the cluster that causes a turnover in the LF. We compare the red sequence LF to that for clusters at z<0.8 correcting the luminosities for passive evolution. The shape of the cluster red sequence LF does not evolve between z=1.62 and z=0.6 but at z<0.6 the faint population builds up significantly. Meanwhile, between z=1.62 to 0.6 the inferred total light on the red sequence grows by a factor of about 2 and the bright end of the LF becomes more populated. We construct a simple model for red sequence evolution that grows the red sequence in total luminosity and matches the constant LF shape at z>0.6. In this model the cluster accretes blue galaxies from the field that are then quenched and subsequently allowed to merge. We find that 3--4 mergers among cluster galaxies during the 4 Gyr between z=1.62 and z=0.6 matches the observed luminosity function evolution between the two redshifts. The inferred merger rate is consistent with other studies of this cluster. Our result supports the picture that galaxy merging during the major growth phase of massive clusters is an important process in shaping the red sequence population at all luminosities.

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