| Abstract: I’ll describe the physical picture underlying multiphase gas, starting with what we mean by “multiphase” in astrophysical systems and where such structure is observed, from the interstellar medium to the circumgalactic medium, and how it fits into the broader baryon cycle governing gas inflows, star formation, and outflows. I’ll then use a few basic ingredients like radiative cooling and turbulence to outline how this structure can form and persist, connecting simple theoretical expectations with the phenomenology inferred from observations.
I’ll also highlight the main challenges in interpreting observations and in modeling multiphase gas across a wide range of scales, including the role of mixing, phase exchange, and unresolved structure, and briefly discuss recent approaches aimed at capturing these processes in simulations. |