Astronomy Colloquium

  Galactic winds are ubiquitous in rapidly star-forming galaxies at low and high redshift.  They shape the stellar mass function, enrich the IGM, and determine in part the evolution of the metal abundance of galaxies.  I will present new work constraining the physics of galactic outflows and feedback processes in these systems.   I will first focus on galactic superwinds driven by very hot gas generated by overlapping supernovae within the host galaxy, and argue that the X-ray observations strongly constrain the mass-loading efficiency, from dwarf starbursts to ultra-luminous infrared galaxies.  These constraints also limit the ability of a hot wind to accelerate cool gas clouds via ram pressure.  I will then show in what regimes hot winds become radiative on 1-100kpc scales and discuss the observational implications.  I will then focus on momentum injection by supernovae and radiation pressure of starlight on dust grains.  I will discuss new work on the phenomenology of high redshift galaxies and their generalized Eddington limit for expelling gas.  Finally, I will discuss a set of numerical experiments to understand the coupling between radiation and matter in highly optically-thick environments relevant for dense starburst nuclei and the self-gravitating disks that attend the fueling of active galactic nuclei.