Speaker: Dr. Cassi Lochhaas, Space Telescope Science Institute
Abstract: The region of space surrounding galaxies, the circumgalactic medium (CGM), is the site of all gas flows into and out of galaxies and therefore responsible for regulating or promoting galaxy growth. It has been only in the past couple decades that we have been able to observe this tenuous medium, and even more recently that we have been able to resolve it in cosmological simulations. I will discuss the classical theories for the CGM’s role in galaxy evolution and how my work has shown these theories need serious revision in light of new simulations. Using the Figuring Out Gas & Galaxies In Enzo (FOGGIE) simulations that resolve the CGM of Milky Way-like galaxies in exquisite detail, I will describe how dynamic gas motions in the CGM – turbulence, rotation, and bulk radial flows – drive the galactic ecosystem out of hydrostatic equilibrium and drive its temperature away from the virial temperature, ultimately affecting how galaxies accrete new gas to convert into stars. These results hint at a new paradigm of non-equilibrium galaxy evolution, where the commonly-assumed balance between gas flows and star formation in galaxies is actually an emergent phenomenon that appears only through averaging over large scales in space and time.