Gwen Rudie (Carnegie) "The Circumgalactic Medium of Star-Forming Galaxies during Cosmic Noon"
The exchange of baryons between galaxies and their surrounding intergalactic medium (IGM) 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 KBSS is optimized to trace the cosmic peak of star formation (z~2-3), combining high-resolution spectra of hyperluminous QSOs with densely-sampled galaxy redshift surveys surrounding each QSO sightline. I will present new detailed studies of metal-enriched absorbing gas in the high-z CGM, highlighting the gas kinematics and thermal properties and the diversity of physical conditions found close to galaxies. Collectively, these data constrain the nature and sphere of influence of galaxy-scale outflows, intergalactic accretion, and their evolution as a function of time.
Priya Natarajan (Yale) "Stress-Testing the Cold Dark Matter Paradigm"
The key elusive cosmic constituents - dark matter, dark energy and black holes - play a fundamental role in shaping the visible universe. In this talk, I will discuss the current status of our understanding of dark matter and the key open questions. Gravitational lensing by clusters of galaxies offers a powerful way to map dark matter and the high quality of current data permits detailed comparison with simulations of structure formation. Current deep Hubble Space Telescope data in combination with ground-based follow-up spectroscopy permit the construction of high-resolution lensing derived maps of dark matter that can be used to stress-test the cold dark matter model. I will present results from recent work that reveal tensions between the predictions of the standard cold dark matter theory and observations of cluster lenses.