The Galaxy-Dark Matter Connection: A Cosmological Perspective
  We present a method that uses observations of galaxies to simultaneously
constrain cosmological parameters and the galaxy-dark matter connection (aka
halo occupation statistics). The latter describes how galaxies are distributed
over dark matter haloes, and is an imprint of the poorly understood physics of
galaxy formation. A generic problem of using galaxies to constrain cosmology is
that galaxies are a biased tracer of the mass distribution, and this bias is
generally unknown. The great advantage of simultaneously constraining cosmology
and halo occupation statistics is that this effectively allows cosmological
constraints marginalized over the uncertainties regarding galaxy bias. Not only
that, it also yields constraints on the galaxy-dark matter connection, this
time properly marginalized over cosmology, which is of great value to inform
theoretical models of galaxy formation. We use a combination of the analytical
halo model and the conditional luminosity function to describe the galaxy-dark
matter connection, which we use to model the abundance, clustering and
galaxy-galaxy lensing properties of the galaxy population. We use a Fisher
matrix analysis to gauge the complementarity of these different observables,
and present some preliminary results from an analysis based on data from the
Sloan Digital Sky Survey. Our results are complementary to and perfectly
consistent with the results from the 7 year data release of the WMAP mission,
strengthening the case for a true 'concordance' cosmology.
