"The impact of feedback and the hot halo on the rates of gas accretion on to galaxies" - Correa et al. (2018)
My former student, and now high flying postdoctoral researcher at Leiden University, Dr Camila Correa answered one of the basic questions in galaxy formation in this paper - how does gas get to the galaxy from the larger Universe? The simple answer is, it depends. Essentially the bigger you are the more gas you can pull in, until you get to something the size of our Milky Way, when the `accretion' rate of material infalling then flattens out. This picture is complicated as the hot gas halo surrounding a galaxy is responsible for preventing new material from infalling as it shocks against the hot halo. The amount of the hot halo depends on the type of energetic events within a galaxy, be it exploding stars (supernovae) or accreting black holes (AGN). A beautiful bit of work that will inform theorists and observers for years to come!