A systematic search for galaxy protocluster cores at the transition epoch of their star formation activity
A systematic search for galaxy protocluster cores at the transition epoch of their star formation activity
复制标题
在恒星形成活动过渡时期系统地寻找星系原团簇核心
DOI：
10.1093/mnras/stac1049
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发表时间：
2022
影响因子：
4.8
通讯作者：
R.
中科院分区：
文献类型：
--
作者：
Ando;M. Shimasaku;K.;Momose;R.;Ito;K.;Sawicki;M.;Shimakawa;R.
z = 1.5的红移是原星系团从恒星形成阶段进入淬灭阶段的过渡时期，因此是研究淬灭粒子数增加的合适时期。我们将“核心”定义为给定PC中最大的光环，环境影响可能最有效地发挥作用，并在1 <z< 1.5处搜索核心。我们使用斯巴鲁超超级相机的宽（有效区域）和深（）光学调查的测光红移目录。对于log（M*/M）> 11.3的星系作为PC核的中心星系，我们通过聚类分析估计了它们的平均晕质量，发现log（Mh/M）= 13.7。IllustrisTNG模拟的预期质量增长和周围观察到的超密度表明，我们发现的PC核心是当今星系团的祖先。将我们的星系样本分为红星系和蓝星系，我们计算了恒星质量函数（SMF）和红星系分数。PC核心的SMF比场更重，这意味着早期的高质量星系形成和低质量星系的分裂。我们还发现，红色部分增加恒星质量，与恒星质量依赖的环境淬灭最近发现atz> 1。有趣的是，虽然红色和蓝色中心的核心有类似的晕质量，只有那些红色中心显示出显着的红色部分相比，外地过剩，这表明一个整合效应。PC核的一些观测特征可能暗示了这种一致性是由组装偏差引起的。
The redshift ofz∼ 1.5 is the transition epoch of protoclusters (PCs) from the star-forming phase into the quenching phase, and hence an appropriate era to investigate the build up of the quenched population. We define a ‘core’ as the most massive halo in a given PC, where environmental effects are likely to work most effectively, and search for cores at 1 <z< 1.5. We use a photometric redshift catalogue of a wide (effective area of) and deep () optical survey with Subaru Hyper-Suprime Cam. Regarding galaxies with log (M*/M⊙) > 11.3 as the central galaxies of PC cores, we estimate their average halo mass by clustering analysis and find it to be log (Mh/M⊙) ∼ 13.7. An expected mass growth by the IllustrisTNG simulation and the observed overdensities around them suggest that the PC cores we find are progenitors of present-day clusters. Classifying our galaxy sample into red and blue galaxies, we calculate the stellar mass function (SMF) and the red galaxy fraction. The SMFs in the PC cores are more-top heavy than field, implying early high-mass galaxy formation and disruption of low-mass galaxies. We also find that the red fraction increases with stellar mass, consistent with stellar mass dependent environmental quenching recently found atz> 1. Interestingly, although the cores with red and blue centrals have similar halo masses, only those with red centrals show a significant red fraction excess compared to the field, suggesting a conformity effect. Some observational features of PC cores may imply that the conformity is caused by assembly bias.