半解析模型预测从群体到群体的质量分离
Semi-Analytic Model Predictions of Mass Segregation from Groups to Clusters
摘要：
利用高分辨率的模拟，加上一个国家的最先进的半解析模型的星系形成，我们探测的质量分离的星系群和星系团，专注于哪些物理机制是驱动它。我们发现的证据，质量分离的星系群和星系团的维里半径，无论是看星系恒星质量和subhalo质量。造成这种现象的物理机制与动力学摩擦是一致的，这是一种拖曳力，它使质量更大的星系更快地接近晕的最内部区域。与观测结果不一致的是，我们没有发现样本中包含低质量星系，低至恒星质量$M_* = 10^9 \, M_{\odot}$，以改变中等和大质量星系所显示的整体趋势。此外，恒星剥离以及星系吸积后的生长，不有助于塑造质量分离或混合的径向质量分布。超过维里半径，我们发现一个“反质量分离”的群体，逐步削弱集群。新物体的不断吸积和最近的合并事件发挥着不同的作用，这取决于吸积物质所落的晕质量。
英文摘要：
Taking advantage of a high-resolution simulation coupled with a state-of-art semi-analytic model of galaxy formation, we probe the mass segregation of galaxies in groups and clusters, focusing on which physical mechanisms are driving it. We find evidence of mass segregation in groups and clusters up to the virial radius, both looking at the galaxy stellar mass and subhalo mass. The physical mechanism responsible for that is consistent with dynamical friction, a drag-force that brings more massive galaxies faster towards the innermost regions of the halo. At odds with observational results, we do not find the inclusion of low-mass galaxies in the samples, down to stellar mass $M_* = 10^9 \, M_{\odot}$, to change the overall trend shown by intermediate and massive galaxies. Moreover, stellar stripping as well as the growth of galaxies after their accretion, do not contribute either in shaping mass segregation or mixing the radial mass distribution. Beyond the virial radius we find an "anti-mass segregation" in groups that progressively weakens in clusters. The continuous accretion of new objects and recent merger events play a different role depending on the halo mass onto which accreting material is falling.
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