The Physics department colloquia are usually on Friday afternoons at 3:30 pm in Lapham Hall Room 160. Coffee and cookies are served at 3:15 pm in the same room. Anyone is welcome.

The Fate of Ionizing Radiation from Massive Stars in Star-Forming Galaxies
Dr. Sally Oey, Dept. of Astronomy, University of Michigan

The fate of ionizing radiation from massive stars has fundamental consequences on scales ranging from the physics of circumstellar disks to the ionization state of the entire universe. On galactic scales, the radiative feedback from massive stars is a major driver for the energetics and phase balance of the interstellar gas in star-forming galaxies. While even starburst galaxies appear to be largely optically thick in the hydrogen Lyman continuum, nebular ionization structure shows that significant populations of star-forming regions within galaxies are optically thin, powering the diffuse, warm ionized medium.

I will discuss our multi-faceted work to clarify our understanding of the fate of stellar ionizing radiation and diagnostics for probing Lyman continuum optical depth in star-forming galaxies, from satellite galaxies of the Milky Way to starbursts.