X-Ray Emitting Active Galactic Nuclei from z = 0.6-1.3 in the
  Intermediate and High-Density Environments of the ORELSE Survey
  We studied AGN activity in twelve LSSs in the ORELSE survey, at 0.65<z<1.28,
using a combination of Chandra observations, optical and NIR imaging and
spectroscopy. We located a total of 61 AGNs across our sample that were
successfully matched to optical counterparts in the LSSs. Seeking to study AGN
triggering mechanisms, we examined the spatial distribution of the AGNs and
their average spectral properties. We found that AGN populations across our
sample had less time since the last starburst than the overall galaxy
populations. We did not find any relation between AGN activity and location
within the LSSs, suggesting triggering mechanisms which depend on global
environment are at most sub-dominant. To focus on differences between our AGNs,
we grouped them into four sub-samples based on the spectral properties of their
parents LSSs. We found one of the sub-samples, SG0023 & SC1604, stood out from
the others: AGNs in this sample were disproportionately luminous, their average
time since the last starburst event was the smallest, despite the fact that
this was not true of the overall galaxy population in those LSSs, and both the
AGNs and the overall galaxy population had the largest fraction of close
kinematic pairs, which indicates a higher rate of galaxy mergers and
interactions. These results suggest that major mergers are driving AGN activity
in SG0023 & SC1604, while other processes are likely triggering less luminous
AGNs in the rest of our sample. Additionally, minor mergers are unlikely to
play a significant role, since the same conditions that lead to more major
mergers should should also lead to more minor mergers, which is not observed in
SG0023 & SC1604.
