A VLT spectroscopic survey of RX J0152.7-1357, a forming cluster of galaxies at z = 0.837
A VLT spectroscopic survey of RX J0152.7-1357, a forming cluster of galaxies at z = 0.837
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对 RX J0152.7-1357（z = 0.837 处正在形成的星系团）进行的 VLT 光谱巡天
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发表时间：
2004
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通讯作者：
T. Broadhurst
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作者：
R. Demarco;R. Demarco;P. Rosati;C. Lidman;N. Homeier;Evan Scannapieco;Narciso Benitez;V. Mainieri;M. Nonino;M. Girardi;S. Stanford;S. Stanford;P. Tozzi;S. Borgani;J. Silk;G. Squires;T. Broadhurst
本文介绍了对RX J0152.7-1357的广泛光谱观测结果，RX J0152.7-1357是已知最大的距离星系团之一。在ESO甚大望远镜（VLT）上使用FORS 1和FORS 2进行的多目标光谱学使我们能够测量星系团场中的200多个红移，并确认102个星系为星系团成员。星团的平均红移为z = 0.837 ± 0.001，我们估计整个星团星系分布的速度色散为1600 km s −1。星系团成员的分布明显是不规则的，有两个主要的星系团跟随钱德拉绘制的X射线星系团发射图。第三个星系团位于中央结构的东部，并且在星系团的红移处也被发现。这两个主星团的速度色散分别为10919和10737 km s −1，这两个星团的奇特速度表明它们将合并成一个更大的星团。观察到成员星系的星星形成活动存在分离现象。所有的恒星形成星系都位于高密度峰之外，这些峰只由被动星系组成。在该星系团的外围观测到一群红色星系（属于星系团红色序列），它们具有清晰的星暴后光谱特征和（OII）（λ3727）发射线。在ROSAT和BeppoSAX观测中，曾与团内介质的X射线弥散辐射相混淆的两个活动星系核，被认为是团的成员。
We present the results of an extensive spectroscopic survey of RX J0152.7-1357, one of the most massive dis- tant clusters of galaxies known. Multi-object spectroscopy, carried out with FORS1 and FORS2 on the ESO Very Large Telescope (VLT), has allowed us to measure more than 200 redshifts in the cluster field and to confirm 102 galaxies as cluster members. The mean redshift of the cluster is z = 0.837 ± 0.001 and we estimate the velocity dispersion of the overall cluster galaxy distribution to be ∼1600 km s −1 . The distribution of cluster members is clearly irregular, with two main clumps that follow the X-ray cluster emission mapped by Chandra. A third clump of galaxies to the east of the central structure and at the cluster redshift has also been identified. The two main clumps have velocity dispersions of ∼919 and ∼737 km s −1 respectively, and the peculiar velocity of the two clumps suggests that they will merge into a single more massive cluster. A segregation in the star formation activity of the member galaxies is observed. All star-forming galaxies are located outside the high-density peaks, which are populated only by passive galaxies. A population of red galaxies (belonging to the cluster red sequence) with clear post-starburst spectral features and (OII) (λ3727) emission lines is observed in the outskirts of the cluster. Two AGNs, which were previously confused with the diffuse X-ray emission from the intracluster medium in ROSAT and BeppoSAX ob- servations, are found to be cluster members.