Dr. Stefanie Walch

University of Florida Astronomy Colloquium - March 18th, 2015

The violent ISM in Milky Way-like disk galaxies

Molecular clouds are cold, dense, and turbulent filamentary structures that condense out of the multi-phase interstellar medium. They are also the sites of star formation. The minority of new-born stars is massive, but these stars are particularly important for the fate of their parental molecular clouds. I will introduce the physics which governs the multi-phase ISM. This includes heating and cooling as well as supersonic turbulence. Furthermore, I will present results from high-performance, three-dimensional simulations that show the formation and dispersal of molecular clouds and the ISM within representative pieces of disk galaxies. Apart from stellar feedback, self-gravity, an external stellar potential, and magnetic fields, we employ an accurate description of gas heating and cooling as well as a small chemical network including molecule formation and self-shielding. We study the impact of the supernova rate and the positioning of the supernova explosions with respect to the molecular gas in a well defined set of simulations. This allows us to draw conclusions on structure of the multi-phase ISM, the amount of molecular gas formed, and the onset of galactic outflows.