Understanding the unique assembly history of central group galaxies
Understanding the unique assembly history of central group galaxies
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了解中心星系团的独特组装历史
DOI：
10.1088/0004-637x/797/1/62
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
Carlo Nipoti
中科院分区：
文献类型：
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作者：
Benedetta Vulcani;Kevin Bundy;Claire Lackner;Alexie Leauthaud;Tommaso Treu;Simona Mei;Lodovico Coccato;Jean Paul Kneib;Matthew Auger;Carlo Nipoti
大质量晕中的中心星系（CGs）生活在独特的环境中，其形成历史与宿主晕的形成历史密切相关。在本星团中，它们在固定恒星质量M*时具有较大的尺寸（R e）和较低的速度色散（σ），并且在固定σ时的R e比场星系和卫星星系（非cgs）大得多。利用从COSMOS调查中选择的群星系的光谱观测，我们比较了z ~ 0.6处早期型cg和非cg的动态尺度关系，以区分产生所需演化的可能机制。与具有相似M*的非cg相比，cg在固定σ下有系统地向更大的re偏移。CG R e - M*关系也显示出差异，主要是由一个亚群（~ 15%）具有大R e的星系驱动的，而M* -σ关系则无法区分。当采用双ssamrsic剖面时，这些结果更加突出，因为双ssamrsic剖面更适合星系外部区域的光。他们认为，即使是群体尺度的CGs也可以通过这些红移产生扩展分量，从而将总R e和M*估计增加约2倍。为了探索我们的样本和集群cg之间的进化联系，我们还分析了z ~ 0.6和z ~ 0的两个集群样本。我们发现类似的结果更大的光晕在相当的z，但更明显的CG缩放关系在低z。因此，外层成分的快速、后期的吸积，可能是通过卫星的剥离和吸积来实现的，这似乎是区分星云演化历史的一个关键特征。
Central galaxies (CGs) in massive halos live in unique environments with formation histories closely linked to that of the host halo. In local clusters, they have larger sizes (R e) and lower velocity dispersions (σ) at fixed stellar mass M*, and much larger R e at a fixed σ than field and satellite galaxies (non-CGs). Using spectroscopic observations of group galaxies selected from the COSMOS survey, we compare the dynamical scaling relations of early-type CGs and non-CGs at z∼ 0.6 to distinguish possible mechanisms that produce the required evolution. CGs are systematically offset toward larger R e at fixed σ compared to non-CGs with similar M*. The CG R e–M* relation also shows differences, primarily driven by a subpopulation (∼ 15%) of galaxies with large R e, while the M*–σ relations are indistinguishable. These results are accentuated when double Sérsic profiles, which better fit light in the outer regions of galaxies, are adopted. They suggest that even group-scale CGs can develop extended components by these redshifts that can increase total R e and M* estimates by factors of∼ 2. To probe the evolutionary link between our sample and cluster CGs, we also analyze two cluster samples at z∼ 0.6 and z∼ 0. We find similar results for the more massive halos at comparable z, but much more distinct CG scaling relations at low-z. Thus, the rapid, late-time accretion of outer components, perhaps via the stripping and accretion of satellites, would appear to be a key feature that distinguishes the evolutionary history of CGs.