An enhanced abundance of bright galaxies in protocluster candidates at z ~ 3-5
An enhanced abundance of bright galaxies in protocluster candidates at z ~ 3-5
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z ~ 3-5 处原星系团候选者中明亮星系的丰度增加
DOI：
10.1093/mnras/stad3162
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发表时间：
2024
影响因子：
4.8
通讯作者：
Toshikawa J
中科院分区：
文献类型：
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作者：
Toshikawa J
我们提出了一种覆盖∼3 toz∼5的原簇搜索方案，该方案是基于超级凸轮斯巴鲁战略计划和CFHT大区域U波段深度探测的组合。我们在深/超深层区域每个单位红移确定了大约30个原星系团候选者。原星系团候选被选为具有显著增强的失落星系表面密度的区域。通过这个大样本，我们描述了它们各自成员星系的性质。我们比较了原星系团候选星系和同龄场星系中失落星系的数目。静止的紫外线(UV)明亮星系在原星系团候选星系中过多，这一趋势在所研究的整个红移范围内都可以看到。我们没有发现证据表明它们在候选原星团中的空间分布与较暗的对应星系不同，也没有证据表明它们的紫外线颜色与相同亮度的场星系的不同。宇宙学模拟预测了这种亮端过剩，主要原因是更多的大质量星系，在固定质量下恒星形成活动(因此紫外线发射)的增强只有很小的贡献。我们观测样本的U-to-KSED模型支持这一解释。这种在数量上的环境差异在∼5已经到位，没有明显的红移依赖于所探测的回顾时间的范围。这些观测结果和模型预测表明，宇宙时钟在高密度环境中领先。
We present a protocluster search coveringz∼ 3 toz∼ 5 based on the combination of the Hyper SuprimeCam Subaru Strategic Programme and the CFHT Large AreaU-band Deep Survey. We identify about 30 protocluster candidates per unit redshift over thearea of the Deep/UltraDeep layer. Protocluster candidates are selected as regions with a significantly enhanced surface density of dropout galaxies. With this large sample, we characterize the properties of their individual member galaxies. We compare the number counts of dropout galaxies in protocluster candidates with that of coeval field galaxies. Rest-frame ultraviolet (UV) bright galaxies are overabundant in protocluster candidates, a trend seen across the full redshift range studied. We do not find evidence for their spatial distribution within protocluster candidates to be distinct from their fainter counterparts, nor for their UV colour to be different from that of field galaxies with the same brightness. Cosmological simulations predict this bright-end excess, with the main cause being a richer population of massive galaxies, with only a minor contribution from an enhancement in star formation activity (and therefore UV emission) at fixed mass.U-to-KSED modelling of our observed samples supports this interpretation. This environmental differentiation in number counts is already in place atz∼ 5, with no significant redshift dependence over the range in lookback times probed . These observational results and model predictions suggest that the cosmic clock is ahead in high-density environments.