A large difference in the progenitor masses of active and passive galaxies in the EAGLE simulation
A large difference in the progenitor masses of active and passive galaxies in the EAGLE simulation
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DOI：
10.1093/mnrasl/slw137
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发表时间：
2016-04
影响因子：
4.8
通讯作者：
B. Clauwens;M. Franx;J. Schaye
中科院分区：
文献类型：
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作者：
B. Clauwens;M. Franx;J. Schaye
星系的累积数密度匹配是一种在观测上将后代星系与其典型的主祖星系在高红移上联系起来，从而评估星系性质演化的方法。由于单个星系的恒星质量增长历史中存在星系合并和散射的问题，这种方法的准确性受到限制。Behroozi等人（2013）基于观测星系与Bolshoi纯暗物质模拟的丰度匹配，对该方法进行了改进。EAGLE宇宙水模拟非常适合测试这种方法，因为它再现了观测到的星系恒星质量函数和被动分数的演化。我们发现与Behroozi等人（2013）对z = 0星系主祖先完整样本的方法一致，但我们也发现对当前恒星形成速率的强烈依赖。恒星质量高达10^10.75 Msun的被动星系与相同质量的活跃星系有着完全不同的中间质量历史。如果我们只选择中心星系，这种差异仍然存在。这意味着累积数密度法应该分别应用于活动星系和被动星系。即便如此，典型的z = 0星系的主祖星系在z = 2的恒星质量已经跨越了两个数量级。
Cumulative number density matching of galaxies is a method to observationally connect descendent galaxies to their typical main progenitors at higher redshifts and thereby to assess the evolution of galaxy properties. The accuracy of this method is limited due to galaxy merging and scatter in the stellar mass growth history of individual galaxies. Behroozi et al. (2013) have introduced a refinement of the method, based on abundance matching of observed galaxies to the Bolshoi dark-matter-only simulation. The EAGLE cosmological hydro-simulation is well suited to test this method, because it reproduces the observed evolution of the galaxy stellar mass function and the passive fraction. We find agreement with the Behroozi et al. (2013) method for the complete sample of main progenitors of z = 0 galaxies, but we also find a strong dependence on the current star formation rate. Passive galaxies with a stellar mass up to 10^10.75 Msun have a completely different median mass history than active galaxies of the same mass. This difference persists if we only select central galaxies. This means that the cumulative number density method should be applied separately to active and passive galaxies. Even then, the typical main progenitor of a z = 0 galaxy already spans two orders of magnitude in stellar mass at z = 2.