在$z\sim 2$上对星系团原核的系统搜寻
A Systematic Search for Galaxy Proto-Cluster Cores at $z\sim 2$
摘要：
原星系团核心是原星系团中质量最大的暗物质晕（DMH）。为了揭示核心区域的星系形成，我们在宇宙场的$\sim 1.5\, \mathrm{deg}^{2}$中的$z\sim 2$上寻找原星系团核心。利用大质量星系对（$\log(M_{*}/M_{\odot})\geq11$）作为核的示踪剂，我们发现了75个候选核，其中54%是真实的。聚类分析发现，这些核心具有$2.6_{-0.8}^{+0.9}\times 10^{13}\, M_{\odot}$的平均DMH质量，或污染校正后的$4.0_{-1.5}^{+1.8}\, \times 10^{13} M_{\odot}$。扩展的Press-Schechter模型表明，它们在$z=0$的后代质量与类天炉座或室女座星系团一致。此外，使用IllustrisTNG模拟，我们确认，对大质量星系是很好的示踪剂DMHs质量足以被视为原星系团的核心。然后，我们推导出恒星质量函数（SMF）和静止分数的成员星系的75个候选核心。我们发现，在相同的红移下，核心星系比场星系有更多的头重脚轻的SMF，在$\log(M_{*}/M_{\odot})\gtrsim 10.5$处表现出过剩。静态分数，$0.17_{-0.04}^{+0.04}$在质量范围$9.0\leq \log(M_{*}/M_{\odot})\leq 11.0$，是约三倍高于现场同行，给出了$0.13_{-0.04}^{+0.04}$的环境淬灭效率。这些结果表明，恒星质量组装和淬火加速早在$z\sim 2$在原星团的核心。
英文摘要：
A proto-cluster core is the most massive dark matter halo (DMH) in a given proto-cluster. To reveal the galaxy formation in core regions, we search for proto-cluster cores at $z\sim 2$ in $\sim 1.5\, \mathrm{deg}^{2}$ of the COSMOS field. Using pairs of massive galaxies ($\log(M_{*}/M_{\odot})\geq11$) as tracers of cores, we find 75 candidate cores, among which 54\% are estimated to be real. A clustering analysis finds that these cores have an average DMH mass of $2.6_{-0.8}^{+0.9}\times 10^{13}\, M_{\odot}$, or $4.0_{-1.5}^{+1.8}\, \times 10^{13} M_{\odot}$ after contamination correction. The extended Press-Schechter model shows that their descendant mass at $z=0$ is consistent with Fornax-like or Virgo-like clusters. Moreover, using the IllustrisTNG simulation, we confirm that pairs of massive galaxies are good tracers of DMHs massive enough to be regarded as proto-cluster cores. We then derive the stellar mass function (SMF) and the quiescent fraction for member galaxies of the 75 candidate cores. We find that the core galaxies have a more top-heavy SMF than field galaxies at the same redshift, showing an excess at $\log(M_{*}/M_{\odot})\gtrsim 10.5$. The quiescent fraction, $0.17_{-0.04}^{+0.04}$ in the mass range $9.0\leq \log(M_{*}/M_{\odot})\leq 11.0$, is about three times higher than that of field counterparts, giving an environmental quenching efficiency of $0.13_{-0.04}^{+0.04}$. These results suggest that stellar mass assembly and quenching are accelerated as early as at $z\sim 2$ in proto-cluster cores.
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