X射线探测星系群的质量函数：COSMOS巡天星系演化的环境依赖性
The Galaxy Stellar Mass Function of X-ray detected groups: environmental dependence of galaxy evolution in the COSMOS survey
摘要：
本文研究了160个X射线探测星系群中10^13<Log（M_200/M_sun）<2 × 10^14的恒星质量分布，并与野外星系的质量分布进行了比较，以探讨环境对恒星质量积累的作用。我们强调的差异，建立在现场的被动人口，这印记功能的被动星系的恒星质量分布在Log（M/M_sun）< 10.5。当移动到总质量增加的组时，效果逐渐减弱，表明束缚结构中环境的影响越来越大，这是Log（M/M_sun）< 10.5时淬灭组分积聚的原因。因此，恒星形成星系的恒星质量分布在所有环境中的形状是相似的，并且可以用单个Schechter函数来描述。在红移1之前，几乎没有看到演化。然而，在z=0.2-0.4时，M_200<6x10^13 Msun的星系群（低质量星系群）往往具有恒星形成星系的特征质量，比高质量星系群高出50%;我们将其解释为这类系统中环境过程的减少作用。此外，我们分析了sSFR-Log（M）在组中和田间的分布，发现组在z<0.8时平均显示出较低的sSFR（约0.2 dex）。因此，我们发现，在所有环境中，恒星形成星系的比例都随着红移而增加，但在密度更大的环境中速度更快。最后，我们的分析强调，低质量的集团有一个更高的分数（50%）的恒星质量锁定在恒星形成星系比高质量的系统（即2/3的恒星质量）。
英文摘要：
We study the stellar mass distribution for galaxies in 160 X-ray detected groups of 10^13<Log(M_200/M_sun)<2x10^14 and compare it with that of galaxies in the field, to investigate the action of environment on the build up of the stellar mass. We highlight differences in the build up of the passive population in the field, which imprint features in the distribution of stellar mass of passive galaxies at Log(M/M_sun)< 10.5. The gradual diminishing of the effect when moving to groups of increasing total masses indicates that the growing influence of the environment in bound structures is responsible for the build up of a quenched component at Log(M/M_sun)< 10.5. Differently, the stellar mass distribution of star forming galaxies is similar in shape in all the environments, and can be described by a single Schechter function both in groups and in the field. Little evolution is seen up to redshift 1. Nevertheless at z=0.2-0.4 groups with M_200<6x10^13 Msun (low mass groups) tend to have a characteristic mass for star forming galaxies which is 50% higher than in higher mass groups; we interpret it as a reduced action of environmental processes in such systems. Furthermore we analyse the distribution of sSFR--Log(M) in groups and in the field, and find that groups show on average a lower sSFR (by ~0.2 dex) at z<0.8. Accordingly, we find that the fraction of star forming galaxies is increasing with redshift in all environments, but at a faster pace in the denser ones. Finally our analysis highlights that low mass groups have a higher fraction (by 50%) of the stellar mass locked in star forming galaxies than higher mass systems (i.e. 2/3 of their stellar mass).
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