The Leonard E Parker Center for Gravitation, Cosmology and Astrophysics holds frequent seminars on a broad range of ongoing cosmology and gravitation research topics. Unless otherwise noted, seminars are on Friday afternoons at 1:00 PM in KIRC 2175; there is a gathering for a brown bag lunch at 12:30.

The connection between galaxy environment and the luminosity function slopes of star-forming regions
Dr. David Cook, Caltech

We present the first study of GALEX far-ultraviolet (FUV) luminosity functions of individual star-forming regions within a sample of 258 nearby galaxies spanning a large range in total stellar mass and star formation properties. We identify ~65 000 star-forming regions (i.e. FUV sources), measure each galaxy’s luminosity function, and characterize the relationships between the luminosity function slope (α) and several global galaxy properties. We find that α correlates with global star formation properties, where galaxies with higher star formation rates and star formation rate densities (ΣSFR) tend to have flatter luminosity function slopes. We hypothesize that the flatter slopes in high ΣSFR galaxies is due to higher gas densities and higher star formation efficiencies which result in proportionally greater numbers of bright star-forming regions. In addition, we create a composite luminosity function composed of star-forming regions from many galaxies and find a break in the luminosity function at brighter luminosities. However, we find that this break is an artifact of varying detection limits for galaxies at different distances. Finally, we introduce the Census of the Local Universe (CLU) galaxy survey designed to find tens-of-thousands of new galaxies for targeted aLIGO gravitational wave counterpart searches and demonstrate how these additional star formation laboratories can add to our understanding of how stars form in the local Universe.