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arXiv 2010.04166astro-ph.GA
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IllustrisTNG模拟中星系群和星系团的协调组装

Coordinated Assembly of Galaxy Groups and Clusters in the IllustrisTNG Simulations

Meng Gu, Charlie Conroy, Benedikt Diemer, Lars Hernquist, Federico Marinacci, Dylan Nelson, Rüdiger Pakmor, Annalisa Pillepich, Mark Vogelsberger

摘要:

最近对早型星系光谱的恒星星族分析表明,星系团中心的低质量星系具有大质量星系的高[ $α/\rm Fe$ ]和老年龄特征,而不像星系团和场外围的低质量星系人口。这种现象被称为“协调装配”,以强调大质量星系团中心星系的构建块来自整个低质量星系群的特殊子集。在这里,我们探讨这个想法在IllustrisTNG模拟,特别是TNG 300运行,以了解环境,特别是集群中心,形状的恒星形成历史的静止卫星星系的团体和集群($M_{200c,z=0}\geq10^{13} M_{\odot}$)。用$M_{\star,z=0}\geq10^{10} M_{\odot}$追踪淬灭卫星星系的历史,我们发现那些在更大质量的暗物质晕中,并且位于更靠近主星系的星系,淬灭更早,恒星形成时标更短,恒星年龄更老。恒星形成时标- $M_{\star}$和恒星年龄- $M_{\star}$标度关系与观测结果吻合良好,并预测随晕质量和星团中心距离而变化。对环境的依赖是由于卫星星系的坠落历史:位于靠近星系团中心的星系在$z=0$更大质量的暗物质晕中平均更早地被吸积。在质量较大的晕中,星系的下沉和淬灭时间之间的延迟较短,并且取决于晕在第一次吸积时的质量,这表明群的预处理是卫星淬灭的一个关键方面。

英文摘要:

Recent stellar population analysis of early-type galaxy spectra has demonstrated that the low-mass galaxies in cluster centers have high [$α/\rm Fe$] and old ages characteristic of massive galaxies and unlike the low-mass galaxy population in the outskirts of clusters and fields. This phenomenon has been termed "coordinated assembly" to highlight the fact that the building blocks of massive cluster central galaxies are drawn from a special subset of the overall low-mass galaxy population. Here we explore this idea in the IllustrisTNG simulations, particularly the TNG300 run, in order to understand how environment, especially cluster centers, shape the star formation histories of quiescent satellite galaxies in groups and clusters ($M_{200c,z=0}\geq10^{13} M_{\odot}$). Tracing histories of quenched satellite galaxies with $M_{\star,z=0}\geq10^{10} M_{\odot}$, we find that those in more massive dark matter halos, and located closer to the primary galaxies, are quenched earlier, have shorter star formation timescales, and older stellar ages. The star formation timescale-$M_{\star}$ and stellar age-$M_{\star}$ scaling relations are in good agreement with observations, and are predicted to vary with halo mass and cluster-centric distance. The dependence on environment arises due to the infall histories of satellite galaxies: galaxies that are located closer to cluster centers in more massive dark matter halos at $z=0$ were accreted earlier on average. The delay between infall and quenching time is shorter for galaxies in more massive halos, and depends on the halo mass at its first accretion, showing that group pre-processing is a crucial aspect in satellite quenching.

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