A Catalog of 220 Offset and Dual AGNs: Increased AGN Activation in Major
  Mergers and Separations under 4 kpc
  During galaxy mergers, gas and dust is driven towards the centers of merging
galaxies, triggering enhanced star formation and supermassive black hole (SMBH)
growth. Theory predicts that this heightened activity peaks at SMBH separations
$<$20 kpc; if sufficient material accretes onto one or both of the SMBHs for
them to become observable as active galactic nuclei (AGNs) during this phase,
they are known as offset and dual AGNs, respectively. To better study these
systems, we have built the ACS-AGN Merger Catalog, a large catalog ($N=220$) of
uniformly selected offset and dual AGN observed by $\textit{HST}$ at
$0.2<z<2.5$ with separations $<$20 kpc. Using this catalog, we answer many
questions regarding SMBH -- galaxy coevolution during mergers. First, we
confirm predictions that the AGN fraction peaks at SMBH pair separations $<$10
kpc; specifically, we find that the fraction increases significantly at pair
separations of $<$4 kpc. Second, we find that AGNs in mergers are
preferentially found in major mergers and that the fraction of AGNs found in
mergers follows a logarithmic relation, decreasing as merger mass ratio
increases. Third, we do not find that mergers (nor the major or minor merger
subpopulations) trigger the most luminous AGNs. Finally, we find that nuclear
column density, AGN luminosity, and host galaxy star formation rate have no
dependence on SMBH pair separation or merger mass ratio in these systems, nor
do the distributions of these values differ significantly from that of the
overall AGN population.
