PHYSICS COLLOQUIUM

Tuesday, 9 March 2004
4:00 PM
Broida Hall 1640

Refreshments will be served at 3:30 PM

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DR. CHRISTOPHER IMPEY
University of Arizona

QUASARS AS COSMOLOGICAL PROBES

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.