关于红色序列的建立，聚类告诉我们什么？
What Does Clustering Tell Us About the Buildup of the Red Sequence?
摘要：
我们分析了来自红移范围为0.4<z<2.0的四个样本的红色和蓝色星系的聚类，以测试星系演化到红色序列的各种情况。这些数据来自UKIDSS超深调查，DEEP 2和COMBO-17。使用集群使我们能够确定红色序列的哪一部分是由中央星系和卫星星系组成的。在所有的红移，包括z=0，数据与约60%的卫星星系是红色或淬灭的一致，这意味着约1/3的红色序列是由卫星星系组成的。超过四分之三的红色卫星星系在被吸积到一个更大的晕上后被移动到红色序列中。红色卫星星系的常数比例产生了卫星星系的猝灭时间，它与晕动力学时间tQ ~（1+z）^{-1.5}一样依赖于红移。在四个样本中的三个样本中，数据支持一个模型，其中红色中央星系是所有中央星系的随机样本;没有首选的晕质量尺度，星系从恒星形成过渡到红色和死亡。第四个样本的巨大误差阻碍了任何结论。这些数据排除了恒星形成在临界晕质量以上淬灭的理论模型。合并产生红色中央星系的场景赋予晕质量和中央星系颜色之间较弱的相关性，但即使是合并场景也会在红移超过0.5的情况下与红色星系团形成紧张关系。这些结果表明，中央星系变红的机制是从z=0.5到z=0演化的。
英文摘要：
We analyze the clustering of red and blue galaxies from four samples spanning a redshift range of 0.4<z<2.0 to test the various scenarios by which galaxies evolve onto the red sequence. The data are taken from the UKIDSS Ultra Deep Survey, DEEP2, and COMBO-17. The use of clustering allows us to determine what fraction of the red sequence is made up of central galaxies and satellite galaxies. At all redshifts, including z=0, the data are consistent with ~60% of satellite galaxies being red or quenched, implying that ~1/3 of the red sequence is comprised of satellite galaxies. More than three-fourths of red satellite galaxies were moved to the red sequence after they were accreted onto a larger halo. The constant fraction of satellite galaxies that are red yields a quenching time for satellite galaxies that depends on redshift in the same way as halo dynamical times; t_Q ~ (1+z)^{-1.5}. In three of the four samples, the data favor a model in which red central galaxies are a random sample of all central galaxies; there is no preferred halo mass scale at which galaxies make the transition from star-forming to red and dead. The large errors on the fourth sample inhibit any conclusions. Theoretical models in which star formation is quenched above a critical halo mass are excluded by these data. A scenario in which mergers create red central galaxies imparts a weaker correlation between halo mass and central galaxy color, but even the merger scenario creates tension with red galaxy clustering at redshifts above 0.5. These results suggest that the mechanism by which central galaxies become red evolves from z=0.5 to z=0.
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