Sally Oey, Univ. of Michigan

Massive Stars in Star-Forming Galaxies:  IMF and Radiative Feedback

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. The relative numbers of massive stars are determined by their mass spectrum, described by the Salpeter IMF. This mass function results if star formation is hierarchical such that the smallest star-forming clumps are too small to form the highest mass stars. On galactic scales, the radiative feedback from massive stars is a major driver for the energetics and phase balance of the interstellar medium in star-forming galaxies. While even starburst galaxies appear to be largely optically thick in the Lyman continuum, ionization-parameter mapping shows that significant populations of HII regions within galaxies are optically thin, powering the diffuse, warm ionized medium. I will discuss our multi-faceted work to clarify our understanding of radiative feedback in star-forming galaxies from the Magellanic Clouds to starbursts.

Host:  Martha Haynes