The Global Environment of Small Galaxy Systems
  The main goal of this work is to investigate the influence of environment at
different scales on the properties of galaxies in systems with a low number of
members. To this end we used a catalogue of small galaxy systems comprising
compact and locally isolated pairs, triplets and groups with four and up to six
galaxies. We consider fixed aperture estimators and found that at scales lower
than 5 Mpc pairs are associated to lower density environments than triplets and
groups. Moreover a nearest neighbour approach highlights that triplets prefer
denser environments than pairs and slightly less dense environments than
groups. When considering the position within the cosmic web we found that pairs
and triplets in our sample are associated to void environments while galaxy
groups are more likely to reside in void walls. In agreement with these
results, the system-galaxy cross-correlation function shows that pairs inhabit
environments of lesser density compared to triplets and groups, and on small
scales (< 3Mpc) triplets appear to behave as an intermediate system. Related to
the properties of neighbour galaxies of small systems we found that the
neighbours of groups present a lower fractions of star forming, young stellar
population and blue colour galaxies with respect to neighbours of triplet and
pair systems. These results suggest that differences in the properties of
galaxies in pairs, triplets and groups are not only related to the existence of
an extra galaxy member but also to the large scale environment inhabited by the
systems.
