16 June 2023
Talk title: The Non-Equilibrium Circumgalactic Medium
Time: June 22, 2023 – 4:00pm EST (1:00pm PST)
Speaker: Cassi Lochhaas (STScI)
Meeting ID: 990 8953 7063
Passcode: 276588
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. 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 new, high-resolution cosmological simulations have shown these theories need serious revision. 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 like turbulence, rotation, or bulk radial flows drive the galactic ecosystem out of hydrostatic equilibrium, drive its temperature away from the virial temperature, and disrupt inflowing filaments of gas, ultimately affecting how galaxies accrete new gas to convert into stars. These results suggest that the CGM cannot be well-described using equilibrium assumptions — virial, hydrostatic, pressure, nor ionization equilibrium — on the small scales that quasar absorption observations tend to probe, and imply that perhaps the commonly-assumed balance of gas flows in galaxy evolution models need revision as well.
Connection info and more information about the Diffuse Gas Science interest group can be found on the DGCE SIG web site.