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arXiv 0907.3922astro-ph.CO
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星暴后相位在中等红移星系团红序形成中的作用

On the role of the post-starburst phase in the build-up of the red-sequence of intermediate redshift clusters

Gabriella De Lucia, Bianca M. Poggianti, Claire Halliday, Bo Milvang-Jensen, Stefan Noll, Ian Smail, Dennis Zaritsky

摘要:

本文报道了来自ESO遥远星系团巡天(EDisCS)的一个星系团(cl1232.5-1250)中0.05- 0.5L_* 星系的新的深光谱观测结果。新的数据将这个星系团已经可用的光谱扩展了大约1个星等。该星系团有很大一部分的被动星系,并表现出明确的和相对紧密的颜色-星等关系。在光谱成员中,只有六个星系被归类为“后星暴”(k+a)。对于另一个红移相近的EDisCS团簇,没有发现具有k+a谱的成员。星暴后系统的低测量数量似乎不足以解释观测到的较低红移的微弱红色星系的增加,即使是在考虑新星系进入星系团的情况下。星暴后星系代表了一个可能的通道,将星系从蓝色恒星形成云移动到红色序列,但现有的数据表明,这不是星系团的主要通道。如果附近星系团中红色序列的暗端星系起源于遥远的星系团中观察到的蓝色星系,那么这种转变必须主要通过不会导致后星爆阶段的物理过程发生。此外,我们的数据排除了大量的k+a星系在微弱的星等,发现后发座星系团。

英文摘要:

We present new deep spectroscopic observations of 0.05--0.5 L_* galaxies in one cluster (cl1232.5-1250) drawn from the ESO Distant Cluster Survey (EDisCS) sample, at z = 0.54. The new data extend the spectroscopy already available for this cluster by about 1 magnitude. The cluster has a large fraction of passive galaxies and exhibits a well defined and relatively tight colour-magnitude relation. Among spectroscopic members, only six galaxies are classified as `post-starburst' (k+a). For another EDisCS cluster at similar redshift and with as deep spectroscopy, no member is found to have a k+a spectrum. The low measured numbers of post-starburst systems appear to be inadequate to explain the observed increase of faint red galaxies at lower redshift, even when accounting for the infall of new galaxies onto the cluster. Post-starburst galaxies represent a possible channel to move galaxies from the blue star-forming cloud to the red-sequence, but the available data suggest this is not the dominant channel in galaxy clusters. If the galaxies at the faint end of the red-sequence in nearby clusters originate from the blue galaxies observed in distant galaxy clusters, the transformation must have occurred primarily through physical processes that do not lead to a post-starburst phase. In addition, our data exclude a large population of k+a galaxies at faint magnitudes, as found in the Coma cluster.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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