Studying SMBH — Galaxy Coevolution using Offset and Dual AGN

Galaxy mergers are key events in the process of galaxy evolution. During these events, gas and dust is driven towards the centers of merging galaxies, possibly triggering enhanced star formation and supermassive black hole (SMBH) growth; this heightened activity is thought to peak at SMBH separations <20 kpc. If sufficient material accretes and falls onto one or both of the SMBHs for them to become observable as active galactic nuclei (AGN) during this phase, we call them offset and dual AGN, respectively. Since offset and dual AGN only exist during this time of heightened activity in galaxy mergers, finding and studying them can give insight into the mechanisms of SMBH - galaxy coevolution. However, statistical studies of offset and dual AGN have been limited due to the small number of known systems. To better study these systems, I built the ACS-AGN Merger Catalog, a large catalog (N=220) of uniformly selected offset and dual AGN observed by HST at redshifts from 0.2 to 2.5 with separations <20 kpc. By analyzing this sample, I find that offset and dual AGN are preferentially found in major mergers and that AGN activation peaks at SMBH pair separations <4 kpc. I will discuss these findings, as well as how this type of analysis of SMBH - galaxy coevolution can be expanded by applying machine learning and “big data” analysis techniques to the large, unique datasets of current and future observatories such as the James Webb Space Telescope, Nancy Grace Roman Space Telescope, and Vera Rubin Observatory.