Are compact groups hostile towards faint galaxies?
  The goal of this work is to understand whether the extreme environment of
compact groups can affect the distribution and abundance of faint galaxies
around them. We performed an analysis of the faint galaxy population in the
vicinity of compact groups and normal groups. We built a light-cone mock galaxy
catalogue constructed from the Millennium Run Simulation II plus a
semi-analytical model of galaxy formation. We identified a sample of compact
groups in the mock catalogue as well as a control sample of normal galaxy
groups and computed the projected number density profiles of faint galaxies
around the first- and the second-ranked galaxies. We also compared the profiles
obtained from the semi-analytical galaxies in compact groups with those
obtained from observational data. In addition, we investigated whether the
ranking or the luminosity of a galaxy is the most important parameter in the
determination of the centre around which the clustering of faint galaxies
occurs. There is no particular influence of the extreme compact group
environment on the number of faint galaxies in such groups compared to control
groups. When selecting normal groups with separations between the 1st and 2nd
ranked galaxies similar to what is observed in compact groups, the faint galaxy
projected number density profiles in compact groups and normal groups are
similar in shape and height. We observed a similar behaviour of the population
of faint galaxies in observations and simulations in the regions closer to the
1st and 2nd ranked galaxies. Finally, we find that the projected density of
faint galaxies is higher around luminous galaxies,regardless of the ranking in
the compact group. The semi-analytical approach shows that compact groups and
their surroundings do not represent a hostile enough environment to make faint
galaxies to behave differently than in normal groups.
