Following the crumbs: Statistical effects of Ram Pressure in Galaxies
  We analyse the presence of dust around galaxy group members through the
reddening of background quasars. By taking into account quasar colour and their
dependence on redshift and angular position, we derive mean quasar colours
excess in projected regions around member galaxies and infer the associated
dust mass. For disc-like galaxies perpendicular to the plane of the sky, and at
group-centric distances of the order of the virial radius, thus likely to
reside in the infall regions of groups, we find systematic colour excess values
$e \sim 0.009 \pm 0.004$ for $g-r$ colour. Under the hypothesis of Milky Way
dust properties we derive dust masses of $5.8 \pm 2.5 \cdot 10^8 M_{\odot}/h$,
implying that a large fraction of dust is being stripped from galaxies in their
path to groups.
  We also studied the photometry of member galaxies to derive a colour
asymmetry relative to the group centre direction from a given galaxy. We
conclude that the regions of galaxies facing the centre are bluer, consistent
with the effects of gas compression and star-formation.
  We also combine these two procedures finding that galaxies with a small
colour asymmetry show the largest amounts of dust towards the external regions
compared to a control sample. We conclude that dust removal is very efficient
in galaxies on infall. The fact that galaxies redder towards groups centres are
associated to the strongest reddening of background quasars suggest that gas
removal induced by ram pressure stripping plays a key role in galaxy evolution
and dust content.
