Nov 15, 2012
Gwen Rudie, Caltech
"The Gaseous Environments of High-Redshift Star-Forming Galaxies"
The gaseous environments of galaxies are a crucial but poorly-constrained component of galaxy formation and evolution. The circumgalactic medium (CGM) is the principal reservoir for future gas accretion, and its kinematics and metal enrichment provide vital constraints on the physical properties of galaxy-scale outflows. Characterization of this gas therefore presents a unique window into baryonic flows that are expected to profoundly influence galaxy evolution. I will present results from the Keck Baryonic Structure Survey (KBSS), a unique spectroscopic survey designed to explore the connection between galaxies and intergalactic baryons. The KBSS is optimized to trace the cosmic peak of star formation (z~2-3), combining Keck/HIRES spectra of 15 hyperluminous QSOs with densely-sampled galaxy redshift surveys surrounding each QSO sightline. I will characterize the physical properties of the CGM gas through the spatial distribution, column densities, kinematics, and absorber line widths of ~6000 HI absorbers surrounding ~900 foreground star-forming galaxies within 50 kpc to 3 Mpc of a sightline. These measurements provide clear evidence of gas inflow and outflow as well as accretion shocks or hot outflows from these forming galaxies. I will compare these observations with recent theoretical predictions, highlighting discrepancies that suggest our theoretical picture of gas flows into and out of galaxies is still incomplete.