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北美退伍军人节(Veterans Day),12 日无更新
arXiv 2005.05344astro-ph.GA
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星系团向星系团的吸积

Accretion of Galaxy Groups into Galaxy Clusters

José. A. Benavides, Laura. V. Sales, Mario. G. Abadi

摘要:

我们在$Λ$ CDM中研究了群坍落在星系团的聚集和动力学中的作用。我们从宇宙学流体动力学模拟Illustris中选取位力质量为$M_{\rm 200} \sim 10^{14} \, M_{\odot}$的$10$星系团,并以恒星质量$M_{\star} \geq 1.5 \times 10^8 \, M_{\odot}$跟踪它们的星系。在$z=0$的幸存星系中,$\sim 38\%$的中值是作为星系群的一部分而被吸积的,并且没有直接从磁场中坠落,尽管有显著的星系团到星系团的散射。这些星系团的演化是快速的,它们共同起源的观测特征在$1$ - $3$ Gyr坠落后迅速消失。子结构在促进星系合并发生的条件方面起着主导作用,即使在星团环境中也是如此。随着时间的推移,我们确定(每个集群)的平均$17 \pm 6$合并发生在下落星系协会,其中$7 \pm 3$发生在其集群主机的维里半径。合并的数量在星系团之间显示出很大的分散性,我们最大的星系中有$42$合并,超过了我们的质量截止值。这些合并,这是典型的气体丰富的矮星和气体丰富的组合和气体贫乏的$M_{\star} \sim 10^{11} \, M_{\odot}$,可能有助于显着的$Λ$ CDM内的特定形态的形成,如望远镜(S 0)和蓝致密矮星的群体和集群。

英文摘要:

We study the role of group infall in the assembly and dynamics of galaxy clusters in $Λ$CDM. We select $10$ clusters with virial mass $M_{\rm 200} \sim 10^{14} \, M_{\odot}$ from the cosmological hydrodynamical simulation Illustris and follow their galaxies with stellar mass $M_{\star} \geq 1.5 \times 10^8 \, M_{\odot}$. A median of $\sim 38\%$ of surviving galaxies at $z=0$ are accreted as part of groups and did not infall directly from the field, albeit with significant cluster-to-cluster scatter. The evolution of these galaxy associations is quick, with observational signatures of their common origin eroding rapidly in $1$-$3$ Gyr after infall. Substructure plays a dominant role in fostering the conditions for galaxy mergers to happen, even within the cluster environment. Integrated over time, we identify (per cluster) an average of $17 \pm 6$ mergers that occur in infalling galaxy associations, of which $7 \pm 3$ occur well within the virial radius of their cluster hosts. The number of mergers show large dispersion from cluster to cluster, with our most massive system having $42$ mergers above our mass cut-off. These mergers, which are typically gas rich for dwarfs and a combination of gas rich and gas poor for $M_{\star} \sim 10^{11} \, M_{\odot}$, may contribute significantly within $Λ$CDM to the formation of specific morphologies, such as lenticulars (S0) and blue compact dwarfs in groups and clusters.

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