Physics & Astronomy Evan Schneider NASA Hubble & Lyman Spitzer, Jr. Postdoctoral Fellow, Princeton University: "The origin of multiphase galaxy outflows"

Star-forming galaxies are often observed to have galactic winds - gas that is being ejected from the galaxy in phases ranging from cold molecular clouds to hot X-ray emitting plasma. While these multiphase outflows are routinely observed, theoretically constraining their origin and evolution has proven difficult. Explaining the broad range of observed velocities of the cool ionized phase poses a particular challenge. In this talk, I will discuss a potential dual origin for this cool gas. Through a series of extremely high-resolution simulations run with the GPU-based Cholla code, I will show that in rapidly star-forming galaxies, dense disk gas can be pushed out by the collective effect of supernovae, explaining the low-velocity material. Simultaneously, shredding and mixing of these clouds increases the density of the hot phase of the outflow, leading to large-scale cooling flows that produce high velocity cool gas. In addition to explaining the structure of winds, this mechanism could potentially be the source of cool gas that is ubiquitously found in the inner regions of galaxy halos.