CFHTLenS: The Environmental Dependence of Galaxy Halo Masses from Weak
  Lensing
  We use weak gravitational lensing to analyse the dark matter halos around
satellite galaxies in galaxy groups in the CFHTLenS dataset. This dataset is
derived from the CFHTLS-Wide survey, and encompasses 154 sq. deg of
high-quality shape data. Using the photometric redshifts, we divide the sample
of lens galaxies with stellar masses in the range 10^9 Msun to 10^10.5 Msun
into those likely to lie in high-density environments (HDE) and those likely to
lie in low-density environments (LDE). Through comparison with galaxy
catalogues extracted from the Millennium Simulation, we show that the sample of
HDE galaxies should primarily (~61%) consist of satellite galaxies in groups,
while the sample of LDE galaxies should consist of mostly (~87%) non-satellite
(field and central) galaxies. Comparing the lensing signals around samples of
HDE and LDE galaxies matched in stellar mass, the lensing signal around HDE
galaxies clearly shows a positive contribution from their host groups on their
lensing signals at radii of ~500--1000 kpc, the typical separation between
satellites and group centres. More importantly, the subhalos of HDE galaxies
are less massive than those around LDE galaxies by a factor 0.65 +/- 0.12,
significant at the 2.9 sigma level. A natural explanation is that the halos of
satellite galaxies are stripped through tidal effects in the group environment.
Our results are consistent with a typical tidal truncation radius of ~40 kpc.
