标题： 亮核星系和星团光度隙所追踪的星系团中央星系的等级增长 显示英文标题

标题： The Hierarchical Growth of Bright Central Galaxies and Intracluster Light as Traced by the Magnitude Gap

摘要： 利用在红移范围为$0.20 < z < 0.60$的暗能量巡天（Dark Energy Survey）中识别出的 2800 个星系团样本，我们描述了亮中央星系（BCGs）及其周围团际光（ICL）的层次性形成。 为了量化层次性形成，我们使用恒星质量-暗晕质量（SMHM）关系，将通过质量-富集度关系估计的暗晕质量和 BCG+ICL 系统内的恒星质量进行比较。 此外，我们将亮度差（M14），即在 30 千秒差距范围内测量的 BCG 和在 0.5$R_{200,c}$范围内第四亮的星团成员星系之间的亮度差异，作为该线性关系中的第三个参数。 M14 的加入，它追踪了 BCG 的层次性增长，增加了斜率并减少了固有散射，表明它是 BCG+ICL SMHM 关系中的潜在变量。 此外，在大半径处，与 M14 的相关性减弱。 然而，BCG+ICL 过渡区域（30 千秒差距 - 80 千秒差距）内的恒星光与暗晕质量的相关性最强，并且与 M14 存在统计上显著的相关性。 由于过渡区域和 M14 是独立的测量值，过渡区域可能由于 BCG 的层次性形成而扩大。 此外，由于 M14 和 ICL 都源于层次性增长，我们使用堆叠样本发现，具有较大 M14 值的星团以更大的 ICL 和 BCG+ICL 分数为特征，这表明构建 BCG 恒星质量的合并过程也会增长 ICL。 此外，这可能意味着结合 M14 和 ICL 分数可以识别动态松弛的星团。 显示英文摘要

摘要： Using a sample of 2800 galaxy clusters identified in the Dark Energy Survey across the redshift range $0.20 < z < 0.60$, we characterize the hierarchical assembly of Bright Central Galaxies (BCGs) and the surrounding intracluster light (ICL). To quantify hierarchical formation we use the stellar mass - halo mass (SMHM) relation, comparing the halo mass, estimated via the mass-richness relation, to the stellar mass within the BCG+ICL system. Moreover, we incorporate the magnitude gap (M14), the difference in brightness between the BCG (measured within 30 kpc) and 4th brightest cluster member galaxy within 0.5 $R_{200,c}$, as a third parameter in this linear relation. The inclusion of M14, which traces BCG hierarchical growth, increases the slope and decreases the intrinsic scatter, highlighting that it is a latent variable within the BCG+ICL SMHM relation. Moreover, the correlation with M14 decreases at large radii. However, the stellar light within the BCG+ICL transition region (30 kpc - 80 kpc) most strongly correlates with halo mass and has a statistically significant correlation with M14. Since the transition region and M14 are independent measurements, the transition region may grow due to the BCG's hierarchical formation. Additionally, as M14 and ICL result from hierarchical growth, we use a stacked sample and find that clusters with large M14 values are characterized by larger ICL and BCG+ICL fractions, which illustrates that the merger processes that build the BCG stellar mass also grow the ICL. Furthermore, this may suggest that M14 combined with the ICL fraction can identify dynamically relaxed clusters.