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arXiv 0811.0252astro-ph
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z=0.4-0.8时星暴和星暴后星系的环境

The environments of starburst and post-starburst galaxies at z=0.4-0.8

Bianca M. Poggianti, Alfonso Aragon-Salamanca, Dennis Zaritsky, Gabriella De Lucia, Bo Milvang-Jensen, Vandana Desai, Pascale Jablonka, Claire Halliday, Gregory… 展开作者

Bianca M. Poggianti, Alfonso Aragon-Salamanca, Dennis Zaritsky, Gabriella De Lucia, Bo Milvang-Jensen, Vandana Desai, Pascale Jablonka, Claire Halliday, Gregory Rudnick, Jesus Varela, Steven Bamford, Philip Best, Douglas Clowe, Stefan Noll, Roberto Saglia, Roser Pello, Luc Simard, Anja von der Linden, Simon White

摘要:

后星暴(E+A或k+a)光谱,其特征是异常强的巴耳末吸收线和缺乏发射线,属于恒星形成活动突然结束的星系在过去的Gyr的某个时候。本文利用ESO遥远星系团巡天资料,对星系团、星系团、贫星系团和z=0.4-0.8的星系进行了光谱分析。在这些红移处k+a的发生率强烈地依赖于环境。K+a的优先居住在集群,出乎意料的是,在一个子集的sigma = 200-400公里/秒的群体,那些有一个低分数的[OII]发射器。在这些环境中,20-30%的最近恒星形成星系的恒星形成活动最近被截断。相比之下,在田间、贫困群体和具有高[OII]分数的群体中,k+a的比例更少。k+a星系的发生率与星系团的速度色散相关:质量越大的星系团,k+a的比例越高。尘埃星爆候选者的光谱,具有强大的巴耳末吸收和发射线,呈现出非常不同的环境依赖性从k+a的。它们在z=0.4-0.8的所有环境中都很多,但它们在所有类型的群体中特别多,有利于合并触发的假设。我们的观察结果与之前的建议一致,即星系团k+a星系在过渡阶段被观察到为大质量S 0和Sa星系,从恒星形成的后期类型演变为被动演变的早期类型星系。k+a分数和集群西格玛之间的相关性支持的假设,即在集群中的k+a星系起源于相关的过程中的intraclustermedium,而几种可能性的起源的k+a频率在低[OII]组进行了讨论。(abr.)

英文摘要:

Post-starburst (E+A or k+a) spectra, characterized by their exceptionally strong Balmer lines in absorption and the lack of emission lines, belong to galaxies in which the star formation activity ended abruptly sometime during the past Gyr. We perform a spectral analysis of galaxies in clusters, groups, poor groups and the field at z=0.4-0.8 based on the ESO Distant Cluster Survey. The incidence of k+a's at these redshifts depends strongly on environment. K+a's reside preferentially in clusters and, unexpectedly, in a subset of the sigma = 200-400 km/s groups, those that have a low fraction of [OII] emitters. In these environments, 20-30% of the recently star-forming galaxies have had their star formation activity recently truncated. In contrast, there are proportionally fewer k+a's in the field, the poor groups and groups with a high [OII] fraction. The incidence of k+a galaxies correlates with the cluster velocity dispersion: more massive clusters have higher proportions of k+a's. Spectra of dusty starburst candidates, with strong Balmer absorption and emission lines, present a very different environmental dependence from k+a's. They are numerous in all environments at z=0.4-0.8, but they are especially numerous in all types of groups, favoring the hypothesis of triggering by a merger. Our observations are consistent with previous suggestions that cluster k+a galaxies are observed in a transition phase as massive S0 and Sa galaxies, evolving from star-forming later types to passively evolving early-type galaxies. The correlation between k+a fraction and cluster sigma supports the hypothesis that k+a galaxies in clusters originate from processes related to the intracluster medium, while several possibilities are discussed for the origin of the k+a frequency in low-[OII] groups.(abr.)

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