Astronomy Colloquium / Fall 2007

Hsiao-Wen Chen

(Chicago)

Halo Occupation of Dark Baryons

Observations of QSO absorption-line systems have revealed a wealth of information for the intergalactic medium from the nearby universe all the way to the epoch of reionization. These absorbers offer a powerful tool for mapping the dark universe, but their correlation with known stellar populations has always been ambiguous. I will describe on-going surveys of absorbers and galaxies along common lines of sight toward background quasars, for quantifying the cross-correlation between stars and gas. I will also introduce a new technique we have developed for constraining the baryon content of known dark matter halos based on absorption-line statistics.