The Coevolution of AGN and Their Host Galaxies in Late Stage Mergers

Stemo, Aaron Michael

Graduate Thesis Or Dissertation

The Coevolution of AGN and Their Host Galaxies in Late Stage Mergers Pubblico Deposited

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Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/1r66j241d

Abstract

As galaxies grow and evolve, the supermassive black holes (SMBHs) thought to exist at the center of most galaxies coevolve with them. During periods of growth, these SMBHs can become observable as active galactic nuclei (AGN). My work is focused on studying and understanding the environmental factors that precipitate AGN – galaxy coevolution, and the precise manner in which this coevolution takes place. The first work I present focuses on understanding how a general population of AGN coevolve with their host galaxies; specifically, how AGN luminosity, as a proxy for SMBH growth, relates to host galaxy parameters, such as star formation, in a general AGN population. I then shift my focus to how AGN coevolve with their host galaxies during galaxy merger events. The second work presented is centered around identifying a large sample of AGN host galaxies currently in late-stage mergers — a task that has presented considerable difficulties in the past — and then using this sample to study how AGN coevolve with their host galaxies as a function of their merger environment. The last work I present builds on the previous work by further classifying these AGN host merger systems as either offset AGN or dual AGN systems. This allows me to add nuance to previous findings and further probe key aspects of AGN activation and galaxy coevolution during late stage mergers. Finally, I discuss exciting avenues of future research that can build upon my past work, and expand our knowledge of SMBH – galaxy coevolution. This thesis reflects the entirety of my graduate work, focused on studying the coevolution of AGN and their host galaxies through the rigorous identification and analysis of AGN and the mergers of their host galaxies.

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