The Impact of Galaxy Mergers on AGN Activity

The gas inflows associated with galaxy mergers is considered to fuel supermassive blackhole (SMBH) growth and subsequent fueling of AGNs. However, the connection between merger activity and AGN activity is contested, and investigations are required to confirm whether or not merger activity is a dominant pathway for AGN ignition.nIn this work, we compare merger incidences and AGN incidences for galaxies in the Subaru HSC-SSP, with the aim of investigating the connection between merger activity and AGN activity.We identify mergers in the Subaru HSC-SSP through a fine-tuned version of the deep learning representation model Zoobot, pretrained on citizen science votes on Galaxy Zoo DeCALS images. Zoobot was fine-tuned using synthetic HSC-SSP images from the TNG50 simulations, then used to find merger probabilities in observational images of the HSC-SSP. The AGNs are identified through SED fitting. The spectra is passed through SED fitting code PROSPECT, which can decompose between galaxy and AGN flux contribution of the SED. Galaxies with a flux contribution fraction \(f_{\textrm{AGN}}>0.1\) . We find that merger incidence does not significantly increase among AGNs compared to non-AGNs, meaning that mergers are not necessarily the cause of AGN activity. However, we also find a slight increase in AGN incidence among mergers, indicating that mergers are more likely to be AGN hosts than non-mergers.