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arXiv 1508.04845astro-ph.GA
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最亮星系团星系的演化:形态、恒星质量和环境的影响

Evolution of the brightest cluster galaxies: the influence of morphology, stellar mass and environment

Dongyao Zhao, Alfonso Aragón-Salamanca, Christopher J. Conselice

摘要:

利用von der Linden et al.(2007)的425个附近的布里渊星系团星系(BCGs)样本,我们研究了它们的内部性质(恒星质量、结构参数和形态)与环境之间的关系。更大质量的BCGs倾向于居住在更密集的区域和更大质量的星系团,而不是质量较低的BCGs。此外,CD,这是特别扩展的信封BCGs,似乎更喜欢稍微密集的地区,往往是由更大规模的晕比椭圆BCGs托管。cD型和椭圆型BCGs的恒星质量与环境密度呈平行正相关。然而,在一个固定的环境密度下,cDs的质量平均要高出40%。我们的研究结果,以及以前的研究结果,表明椭圆形和cD BCGs之间的进化联系。我们认为,大多数现今的CD开始他们的生活椭圆,随后在恒星质量和大小的增长,由于合并。在这个过程中,cD信封发展。恒星质量和cDs大小的大分散反映了它们不同的合并历史。BCGs在质量和大小上的增长似乎与它们所居住的结构的等级增长有关:随着群体和集群变得更加密集和庞大,它们中心的BCGs也在增长。这一过程已接近完成,因为本宇宙中的大多数(约60%)BCGs具有cD形态。然而,中间形态类(椭圆和CD之间)的星系的存在表明,一些BCGs的增长和形态转变仍在进行中。

英文摘要:

Using a sample of 425 nearby Brightest Cluster Galaxies (BCGs) from von der Linden et al. (2007), we study the relationship between their internal properties (stellar masses, structural parameters and morphologies) and their environment. More massive BCGs tend to inhabit denser regions and more massive clusters than lower mass BCGs. Furthermore, cDs, which are BCGs with particularly extended envelopes, seem to prefer marginally denser regions and tend to be hosted by more massive halos than elliptical BCGs. cD and elliptical BCGs show parallel positive correlations between their stellar masses and environmental densities. However, at a fixed environmental density, cDs are, on average, ~40% more massive. Our results, together with the findings of previous studies, suggest an evolutionary link between elliptical and cD BCGs. We suggest that most present-day cDs started their life as ellipticals, which subsequently grew in stellar mass and size due to mergers. In this process, the cD envelope developed. The large scatter in the stellar masses and sizes of the cDs reflects their different merger histories. The growth of the BCGs in mass and size seems to be linked to the hierarchical growth of the structures they inhabit: as the groups and clusters became denser and more massive, the BCGs at their centres also grew. This process is nearing completion since the majority (~60%) of the BCGs in the local Universe have cD morphology. However, the presence of galaxies with intermediate morphological classes (between ellipticals and cDs) suggests that the growth and morphological transformation of some BCGs is still ongoing.

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