The Co-evolution of Brightest Cluster Galaxies and Intracluster Light

星系团是宇宙学的重要探测器，是揭开星系形成和演化背后的奥秘以及宇宙中大尺度结构发展的关键人物。该项目旨在研究过去80亿年来最亮星系团星系(BCG)和星系团内光(ICL)的共同演化。这项研究的目的是了解星系形成的物理起源，并量化BCG的大小和恒星质量增长。由于宇宙学的考虑，目标是量化BCG+ICL中恒星重子的比例作为星团质量和红移的函数，以及这个恒星重子比例中星团到星团的变化，并作为星团质量的函数进行最终的(气体和恒星)重子比例的统计。以前的研究有数据限制，需要几个粗略的近似，例如假设所有星系团的质量光比恒定，使用背景减去而不是光谱星系团成员来确定总的星系团光度。之前的工作也缺乏单个星系团的气体和恒星重子数据的组合。拟议的工作将作为一项最终的调查，其中包括星系群和星系团的统计样本的深度光谱分析、X射线数据和深度光度测量，从而用受统计学支配的实际测量取代早先的粗略近似-对科学界广泛重要。在教育方面，拟议的活动将促进对研究生和博士后助理的教学和培训。首席调查员将继续与当地高中共同领导一个外联项目，包括为大约30名高中生举办的研讨会，目标是服务不足的社区。

Clusters of galaxies are important probes of cosmology and are key players in unraveling the mysteries behind galaxy formation and evolution and the development of large scale structure in the Universe. This project aims to investigate the co-evolution of brightest cluster galaxies (BCGs) and intracluster light (ICL) over the past 8 billion years. The study's objectives for understanding galaxy formation are to understand the physical origin of ICL and to quantify the size and stellar mass growth of BCGs. The objectives driven by cosmological considerations are to quantify the fraction of stellar baryons in the BCG plus ICL as a function of cluster mass and redshift and the cluster-to-cluster variation in this stellar baryon fraction and to conduct the definitive census of total (gas plus stellar) baryon fraction as a function of cluster mass.Previous studies have had data limitations requiring several crude approximations, such as assuming a constant mass-to-light ratio for all cluster galaxies and using background subtraction rather than spectroscopic cluster membership to determine the total cluster galaxy luminosity. Previous work has also lacked the combination of gas and stellar baryon data for individual clusters. The proposed work will serve as a definitive survey that includes deep spectroscopy, X-ray data, and deep photometry for the galaxy population and ICL for a statistical sample of clusters, thereby replacing the earlier crude approximations with actual measurements governed by statistics---broadly important to the scientific community.Educationally, the proposed activities will promote teaching and training of a graduate student and a postdoctoral associate. The principal investigator will continue to co-lead an outreach program with local high schools, including a workshop for roughly 30 high school students that targets underserved communities.