Looking at the relation between haloes and galaxies under the lens
  We use an empirical approach to model the stellar mass of galaxies according
to their host dark-matter haloes and subhaloes ('HASH'), where each galaxy
resides in a subhalo taken from a large N-body cosmological simulation. This
approach allows us to study the mass relation between subhaloes and galaxies
(MR) using: the weak lensing signal (WL), the two point auto-correlation
function (CF), and the stellar mass function of galaxies (SMF). Our method is
based on modeling the lensing signal directly from the cosmological simulation,
and should thus be more accurate than other methods based on analytic halo
models. We find that the WL does not provide a strong constraint on the MR,
allowing for more than a factor of 10 freedom in the subhalo mass of central
galaxies, for a given stellar mass. The freedom for satellite galaxies is much
larger, providing a very poor constraint on the fraction of satellite galaxies
(0.05-0.8). These results are not significantly modified when using both the
SMF and WL as constraints. We show that for the most massive galaxies,
observational constraints based on the CF with 0.1 dex errors, are equivalent
to 0.05 dex error in the WL. For intermediate and low mass galaxies the WL and
CF constrain the MR in a different way. Although the WL is currently not adding
much information at these masses, it has the potential of being important using
future, more accurate measurements. The models found here do not match
simultaneously the observed CF and WL signals, and show a limited ability to
match the WL & SMF. We suspect that this is partially due to the cosmological
model assumed here and we therefore adopt a mock WL signal through most of this
work. In comparison to previous models in the literature, the method presented
here is probably more general, as it reveals a larger range of solutions for a
given set of observational constraints [abridged].
