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The Importance of Small-Scale Structure in the CGM and its Impact on Galaxy Evolution


Cameron Hummels (Caltech)

October 30, 2018 @ 12:00 PM - 1:00 PM

The circumgalactic medium (CGM), the tenuous gas filling the halo of a galaxy, acts as the interface between star formation, feedback, and galactic gas accretion, and may contain clues as to what drives galactic evolution.  Despite their many successes in studies of galaxy evolution, cosmological hydrodynamics simulations have been unable to reproduce or explain the detailed structure of the circumgalactic medium.  I will present my work with the FIRE simulations to probe the behavior of the CGM as a function of galaxy mass, environment, resolution, and simulation physics, resulting in both physical insight and reproduction of the elusive COS-Halos O VI observations.  Furthermore, I will introduce the Tempest simulations, a new simulation suite with unprecedented spatial resolution, 500 pc, forced throughout the halo.  I will show why increased resolution in the CGM is so important, how it better resolves the small-scale structure of thermally unstable gas, and how this results in a dramatic increase in cool gas and neutral hydrogen throughout the CGM, with potentially dramatic implications for the fueling and subsequent evolution of the galaxy.