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以及宇宙大尺度结构发展背后奥秘的关键角色。 该项目旨在研究过去80亿年来最亮星系团（BCGs）和团内光（ICL）的共同演化。 该研究的目的是了解星系形成的ICL的物理起源，并量化BCGs的大小和恒星质量增长。 由宇宙学考虑驱动的目标是量化BCG加ICL中恒星重子的分数作为星系团质量和红移的函数，以及这个恒星重子分数在星系团之间的变化，并进行总的（气体加恒星）重子分数作为星系团质量的函数。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光比都是恒定的，并使用背景减除法而不是光谱学的星系团成员资格来确定星系团的总光度。 以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个明确的调查，其中包括深光谱，X射线数据和深测光的星系人口和ICL的统计样本的集群，从而取代早期的粗糙近似与实际测量的统计-广泛重要的科学界。教育，拟议的活动将促进教学和培训的研究生和博士后助理。 首席研究员将继续与当地高中共同领导一个外展计划，包括为大约30名高中生举办一个针对服务不足社区的研讨会。

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.