Astrophysics Seminar: Dr. Cassi Lochhaas, STScI


Location: zoom

Using Simulations to Understand the Structure of the Circumgalactic Medium

Dr. Cassi Lochhaas

The circumgalactic medium (CGM), the region of space surrounding galaxies, is intimately connected to galaxy formation and growth because it regulates gas flows into and out of the galaxy over cosmic time. Observations of the CGM around Milky Way-like galaxies indicate both hot and cold gas coexist there, but the diffuse nature of CGM gas makes the spatial and kinematic structure of these different gas phases difficult to infer from observations. Simulations and analytic models of CGM gas are needed to interpret the observations, determine how cool gas forms and survives in the CGM, and understand how the structure of the CGM impacts the evolution of the galaxy at its center. I will discuss how high-resolution CGM simulations can help distinguish between different models of CGM cool gas formation and show the formation mechanisms differ drastically in high-mass galaxy halos compared to low-mass galaxy halos. In addition, most analytic models of the CGM do not take into account dynamic gas motions, but I will show the nonthermal gas motions are critically important to determining the overall pressure support, structure, and even temperature of the CGM gas in both idealized, isolated galaxy simulations and fully cosmological zoom-in simulations, motivating the need for new, dynamic models informed by simulations.

Hosted by Dr. Lehner

All interested persons are invited to attend remotely—email for information.