Investigating the Effect of Galaxy Interactions on AGN Enhancement at
  $0.5<z<3.0$
  Galaxy interactions and mergers are thought to play an important role in the
evolution of galaxies. Studies in the nearby universe show a higher AGN
fraction in interacting and merging galaxies than their isolated counterparts,
indicating that such interactions are important contributors to black hole
growth. To investigate the evolution of this role at higher redshifts, we have
compiled the largest known sample of major spectroscopic galaxy pairs (2381
with $\Delta V <5000$ km s$^{-1}$) at $0.5<z<3.0$ from observations in the
COSMOS and CANDELS surveys. We identify X-ray and IR AGN among this kinematic
pair sample, a visually identified sample of mergers and interactions, and a
mass-, redshift-, and environment-matched control sample for each in order to
calculate AGN fractions and the level of AGN enhancement as a function of
relative velocity, redshift, and X-ray luminosity. While we see a slight
increase in AGN fraction with decreasing projected separation, overall, we find
no significant enhancement relative to the control sample at any separation. In
the closest projected separation bin ($<25$ kpc, $\Delta V <1000$ km s$^{-1}$),
we find enhancements of a factor of 0.94$^{+0.21}_{-0.16}$ and
1.00$^{+0.58}_{-0.31}$ for X-ray and IR-selected AGN, respectively. While we
conclude that galaxy interactions do not significantly enhance AGN activity on
average over $0.5<z<3.0$ at these separations, given the errors and the small
sample size at the closest projected separations, our results would be
consistent with the presence of low-level AGN enhancement.
