Title:

QUASARS AS COSMOLOGICAL PROBES



Chris Impey
University of Arizona




Abstract:

Unlike techniques that use galaxies as tracers, strong
gravitational lensing and intervening absorption lines can
be studied with nearly equal efficiency over the entire
Hubble time. Strong lensing provides tests of the dark
matter distribution from scales of galaxy nuclei to the
scale of groups of galaxies.  The lenses themselves give
the unique opportunity to study the evolution of galaxies
selected by mass. Well-constrained lens models offer direct
tests of the parameters of the standard cosmological model,
notably the Hubble constant.  Quasar absorption lines can
be used to trace the evolution of the IGM, using the
Lyman-alpha forest, and the enrichment and clustering of
galaxy halos, using metal lines. Paired and multiple quasar
sightlines provide information on the topology of large
scale structure and the spatial geometry of the world
model.