Institute for Advanced Study Astrophysics Seminar

ABSTRACT: Theoretical studies have raised a number of important questions about the roles of gas inflows (accretion) and outflows (feedback) in galaxy evolution. Unfortunately, galactic gas flows are likely to have low densities and hence are difficult to observe with most techniques. However, QSO absorption lines provide sensitive observational probes of galactic flows, and the recent deployment of the Cosmic Origins Spectrograph on HST has greatly expanded this capability by opening access to QSO absorbers in the low-z Universe (where the absorber-galaxy connections can really be studied in detail). This talk will present results from several large HST+COS programs to study galactic flows and missing baryons, including (1) statistical comparisons of the gaseous halos of star-forming galaxies vs. early-type (red and dead) galaxies (2) unambiguous evidence of massive (and escaping) galactic winds from poststarburst galaxies, (3) observations of cool and pristine (low-metallicity) gas in the halos of high-metallicity star-forming galaxies, and (4) first results on the physical conditions of circumgalactic gases.