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.
