Searching for Extreme-BCG Clusters at 0.2 < z < 1.3

Abstract

Active galactic nuclei (AGN) feedback is believed to be responsible for counteracting the formation of the classical “cooling flow”, predicted to be associated with most “cool core” clusters of galaxies. Several studies have shown that many phenomena found in galaxy clusters can be neatly explained by AGN feedback. Yet, the physical mechanism behind AGN feedback remains poorly understood. Careful analysis of clusters with unique characteristics, such as hosting starburst and/or active nuclei, provides an alternative path to tackle the issue of when, and how precisely, AGN feedback impacts clusters.

For my Ph.D. thesis, I show that by finding extreme-BCG clusters we can better understand the processes of cluster formation and evolution. In the first part of my thesis, I conduct an optical survey to discover new extreme-BCG clusters at low redshift. Finding clusters with distinct properties from the survey allows us to make detailed studies of the objects and better understand the formation mechanism of the feedback necessary to sustain long-lived clusters. In the second half, I study a sample of clusters over a large redshift range to find distant objects with extreme BCGs. This enables us to investigate a possible evolution of the feedback across cosmic time, and how the evolution has impacted the growth of all clusters. Thousands of galaxy clusters will be discovered in the coming decade with a certainty that a handful of them will host extreme BCGs. These peculiar objects will play an important role in understanding the complex nature of black hole feedback and galaxy evolution.