VEGAS: VST Early-type GAlaxy Survey. V. IC 1459 group: Mass assembly
  history in low density environments
  This paper is based on the multi-band VST Early-type GAlaxy Survey (VEGAS)
with the VLT Survey Telescope (VST). We present new deep photometry of the
IC1459 group in g and r band. The main goal of this work is to investigate the
photometric properties of the IC1459 group, and to compare our results with
those obtained for other galaxy groups studied in VEGAS, in order to provide a
first view of the variation of their properties as a function of the evolution
of the system. For all galaxies in the IC1459 group, we fit isophotes and
extract the azimuthally-averaged surface-brightness profiles, the position
angle and ellipticity profiles as a function of the semi-major axis, as well as
the average colour profile. In each band, we estimate the total magnitudes,
effective radii, mean colour, and total stellar mass for each galaxies in the
group. Then we look at the structure of the brightest galaxies and faint
features in their outskirts, considering also the intragroup component. The
wide field of view, long integration time, high angular resolution, and
arcsec-level seeing of OmegaCAM@VST allow us to map the light distribution of
IC1459 down to a surface brightness level of 29.26 mag arcsec^{-2} in g band
and 28.85 mag arcsec^{-2} in r band, and out to 7-10 Re, and to detect the
optical counterpart of HI gas around IC1459. We also explore in depth three low
density environments and provide information to understand how galaxies and
groups properties change with the group evolution stage. There is a good
agreement of our results with predictions of numerical simulations regarding
the structural properties of the brightest galaxies of the groups. We suggest
that the structure of the outer envelope of the BCGs, the intra-group light and
the HI amount and distribution may be used as indicators of the different
evolutionary stage and mass assembly in galaxy groups.
