Catalogs of Compact Groups of Galaxies from the Enhanced SDSS DR12
  We apply a friends-of-friends algorithm to an enhanced SDSS DR12
spectroscopic catalog including redshift from literature to construct a catalog
of $1588~N\ge3$ compact groups of galaxies containing 5179 member galaxies and
covering the redshift range $0.01 < z < 0.19$. This catalog contains 18 times
as many systems and reaches 3 times the depth of similar catalog of Barton et
al. (1996). We construct catalogs from both magnitude-limited and
volume-limited galaxy samples. Like Barton et al. (1996) we omit the frequently
applied isolation criterion in the compact group selection algorithm. Thus the
groups selected by fixed projected spatial and rest frame line-of-sight
velocity separation produce a catalog of groups with a redshift independent
median size. In contrast with previous catalogs, the enhanced SDSS DR12 catalog
(including galaxies with $r < 14.5$) includes many systems with $z\leq 0.05$.
The volume-limited samples are unique to this study. The compact group
candidates in these samples have a median stellar mass independent of redshift.
Groups with velocity dispersion $\leq 100$ km s$^{-1}$ show abundant evidence
for ongoing dynamical interactions among the members. The number density of the
volume-limited catalogs agrees with previous catalogs at the lowest redshifts
but decreases as the redshift increases. The SDSS fiber placement constraints
limit the catalog completeness. In spite of this issue the volume-limited
catalogs provide a promising basis for detailed spatially resolved probes of
the impact of galaxy-galaxy interactions within similar dense systems over a
broad redshift range.
