Galactic Accretion through the Dynamic Circumgalactic Medium

The region of space surrounding galaxies, the circumgalactic medium (CGM) is the site of all gas flows into and out of galaxies and is therefore responsible for regulating or promoting galaxy growth.  Observations reveal an interesting diversity of gas properties in this tenuous medium, but it is only recently that we are able to resolve it in cosmological simuations to investigate the physics there.  Using the Figuring Out Gas and 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 like turbulence, rotation, or bulk radial flows drive the galactic ecosystem away from classical assumptions.  These gas flows also disrupt inflowing filaments of gas, ultimately affecting how galaxies accrete new gas to convert into stars.  I will show that upcoming missions that will observe the CGM in emission will be able to directly observe these gas flows, and how simulations can be used to predict and interpret the new data to increase our understanding of the cosmic ecosystem.

Speaker: Cassandra Lochhass, Harvard University