RSAA Colloquia / Seminars / Feast-of-Facts: Thursday, 22 September 2016, 11:00-12:00; Duffield Lecture Theatre

Yuval Birnboim

"Cold flows; when they occur, and how they interact with halos and galaxies."

Gas accreting onto halos and filaments is expected to heat to the "virial temperature" of the perspective structure and produce a hydrostatic, stable atmosphere. I will show that, in fact, accreting gas does not always heat, leading to unstable free falling gas, a.k.a cold flows. The instability of the gas, and subsequent existence of cold flows, depend on the cooling rate and infall velocity of the gas. Once these flows penetrate through a hot halo, supersonic Kelvin Helmholtz instability occurs. I will discuss this non-standard situation. Finally, as cold flows smash into the galaxy, magnetic fields can play a non-trivial role in how this gas actually mixes with the ISM.