Dr. Gwen Rudie, (Dartmouth Class of 2007), Carnegie-Princeton Fellow, Carnegie Observatories,
Title: "The Building Blocks of Early Galaxies in the Juvenile Universe: The Circumgalactic and Interstellar Medium of Star-Forming Systems at 2<z<3"
Abstract: The gaseous component of galaxies is a crucial but poorly-constrained aspect of galaxy formation and evolution. I will present results from the Keck Baryonic Structure Survey (KBSS), a unique spectroscopic survey designed to explore both the physical properties of high-redshift galaxies and the connection between these galaxies and their surrounding intergalactic baryons. The survey utilizes highly-luminous background QSOs to create a precise mapping of intervening gas along single lines of sight in the centers of our survey volumes. The KBSS is optimized to trace the cosmic peak of star formation (z~2-3), combining Keck/HIRES spectra of 15 high-redshift QSOs with densely-sampled galaxy redshift surveys surrounding each QSO sightline. I will characterize the physical properties of the gas within the circumgalactic medium (CGM) 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. I will also discuss KBSS-MOSFIRE, a rest-frame optical spectroscopic survey of galaxies in these same QSO fields. These data provide new insight into the physical properties of HII regions within these star-forming systems, properties which differ in important ways from more local galaxies, providing a new view of galaxies in the juvenile universe.
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