VEGAS: A VST Early-type GAlaxy Survey.VI. The diffuse light in HCG 86
  from the ultra-deep VEGAS images
  Context. In this paper we present ultra deep images of the compact group of
galaxies HCG 86 as part of the VEGAS survey. Aims. Our main goals are to
estimate the amount of intragroup light (IGL), to study the light and color
distributions in order to address the main formation process of the IGL
component in groups of galaxies. Methods. We derived the azimuthally averaged
surface brightness profiles in the g,r and i bands with g - r and r - i average
colors and color profiles for all group members. By fitting the light
distribution, we have extrapolated the contribution of the stellar halos plus
the diffuse light from the brightest component of each galaxy. The results are
compared with theoretical predictions. Results. The long integration time and
wide area covered make our data deeper than previous literature studies of the
IGL in compact groups of galaxies and allow us to produce an extended (~160
kpc) map of the IGL, down to a surface brightness level of about 30
mag/arcsec^2 in the g band. The IGL in HCG 86 is mainly in diffuse form and has
average colors of g - r ~ 0.8 mag and r - i ~ 0.4 mag. The fraction of IGL in
HCG 86 is ~ 16% of the total luminosity of the group, and this is consistent
with estimates available for other compact groups and loose groups of galaxies
of similar virial masses. A weak trend is present between the amount of IGL and
the early-type to late-type galaxy ratio. Conclusions. By comparing the IGL
fraction and colors with those predicted by simulations, the amount of IGL in
HCG 86 would be the result of the disruption of satellites at an epoch of z ~
0.4. At this redshift, observed colors are consistent with the scenario where
the main contribution to the mass of the IGL comes from the
intermediate-massive galaxies.
