Stars Re-Shaping Galaxies

Phil Hopkins (Caltech)

March 22, 2016

–

Abstract: The most fundamental unsolved problems in galaxy formation revolve around “feedback” from massive stars and black holes. I will present new results from the FIRE simulations which combine new numerical methods and physics in an attempt to realistically model the diverse physics of the interstellar medium, star formation, and feedback from stellar radiation pressure, supernovae, stellar winds, and photo-ionization. These mechanisms lead to “self-regulated” galaxy and star formation, in which global correlations such as the Schmidt-Kennicutt law and the global inefficiency of star formation — the stellar mass function — emerge naturally. Within galaxies, feedback regulates the structure of the interstellar medium, but more radically drives outflows which can actually change the dynamics, morphologies, and sizes of galaxies, in addition to transforming cusps into cores and suppressing star formation. We are actually reaching the point where different stellar feedback and stellar types can produce observable differences on extra-galactic scales. Finally, I will discuss where stellar feedback fails, and additional feedback, perhaps from AGN, is really needed to explain observations.