Physics Colloquium: Brilliant past, luminous future: the evergreen lives of star-forming galaxies

Abstract:

In galaxies like our own Milky Way, star formation has continued over the course of several billion years.  However, the rate of interstellar gas conversion to stars is only a tiny fraction of the maximum possible.  The observed "inefficiency" of star formation has been known for many years, but only recently have we begun to understand quantitatively how one generation of stars controls the formation of the next generation through energetic feedback to the interstellar medium.  I will discuss current observations and theory of star formation regulation in a wide range of systems, from individual clouds, to normal galaxies like the Milky Way, to massive high-redshift starbursts.  I will also describe the feedback that star formation produces -- explosive supernovae, powerful winds, and radiation strong enough to overwhelm gravity. Using numerical simulations, we have been able to demonstrate that it is this feedback that keeps galaxies active and full of new stellar life.