Multiphase gas is omnipresent in astrophysical systems but it is notoriously hard to understand and model. During my talk, I will discuss the phenomenon of galactic winds which are are large-scale, multiphase outflows crucial for the galactic ecosystem. The common picture is that the cold gas within them has been accelerated by ram pressure forces. However, reproducing this observation in hydrodynamical simulations has proven to be challenging – simply because the destruction time is shorter than the acceleration time. I will show some analytical estimates and results from recent (magneto-)hydrodynamics simulations in combination with a novel model of dark matter which suggest a solution to this classical “entrainment problem”. I will conclude by discussing potential implications for larger scale galactic simulations, and observables of cold gas in the surroundings of galaxies. Time provided, I would like to in particular point out that the Lyman-alpha line can be a powerful probe of the distribution of neutral hydrogen which reveals problems of most current galactic simulations.

Host: David Barnes