Activity in Galactic Nuclei of Compact Group Galaxies in the Local
  Universe
  We study the nuclear activity of galaxies in local compact groups. We use a
spectroscopic sample of 238 galaxies in 58 compact groups from the Sloan
Digital Sky Survey data release 7 to estimate the fraction of AGN-host galaxies
in compact groups, and to compare it with those in cluster and field regions.
We use emission-line ratio diagrams to identify AGN-host galaxies, and find
that the AGN fraction of compact group galaxies is 17-42% depending on the AGN
classification method. The AGN fraction in compact groups is not the highest
among the galaxy environments. This trend remains even if we use several
subsamples segregated by galaxy morphology and optical luminosity. The AGN
fraction for early-type galaxies decreases with increasing galaxy number
density, but the fraction for late-type galaxies changes little. We find no
mid-infrared detected AGN-host galaxies in our sample of compact groups using
Wide-field Infrared Survey Explorer data. These results suggest that the
nuclear activity of compact group galaxies (mostly early types) is not strong
because of lack of gas supply even though they may experience frequent
galaxy-galaxy interactions and mergers that could trigger nuclear activity.
