Comparing galaxy populations in compact and loose groups of galaxies
  We perform a comparison of the properties of galaxies in compact groups,
loose groups and in the field to deepen our understanding of the physical
mechanisms acting upon galaxy evolution in different environments. We select
samples of galaxies in compact groups identified by McConnachie et al., loose
groups identified by Zandivarez and Martinez, and field galaxies from the Sloan
Digital Sky Survey. We compare properties of the galaxy populations in these
different environments: absolute magnitude, colour, size, surface brightness,
stellar mass and concentration. We also study the fraction of red and early
type galaxies, the luminosity function, the colour-luminosity and
luminosity-size relations. The population of galaxies in compact groups differ
from that of loose groups and the field. The fraction of read and early type
galaxies is higher in compact groups. On average, galaxies in compact groups
are systematically smaller, more concentrated and have higher surface
brightness than galaxies in the field and in loose groups. For fixed absolute
magnitude, or fixed surface brightness, galaxies in compact groups are smaller.
The physical mechanisms that transform galaxies into earlier types could be
more effective within compact groups given the high densities and low velocity
dispersion that characterise that particular environment, this could explain
the large fraction of red and early type galaxies we found in compact groups.
Galaxies inhabiting compact groups have undergone a major transformation
compared to galaxies that inhabit loose groups.
