Example SDSS postage stamp images for representative galaxies in Brians sample, placed according to their positions in our parameter space. Top panel shows face-on galaxies, bottom panel shows edge-on galaxies (the upper-leftmost bins are omitted in the bottom panel since there are very few highly flattened galaxies in this region of parameter space). Background contours show the overall galaxy distributions.

Brian Devour has successfully defended his PhD thesis, entitled Dust and its Effects on Measures of Galaxy Properties. Brian uses near-IR and mid-IR survey datasets to select galaxies in an inclination-independent way and then quantifies how their properties change as a function of galaxy inclination as a non-parametric measure of attenuation. In addition to his two completed papers, Devour & Bell (2016; Global dust attenuation in disc galaxies: strong variation with specific star formation and stellar mass, and the importance of sample selection) and Devour & Bell (2017; Revealing strong bias in common measures of galaxy properties using new inclination-independent structures), Brian added two new chapters. One chapter carefully develops, tests and generates error estimates for his new inclination-independent galaxy structure metrics (the metric was introduced in Devour & Bell 2017). The other chapter carries out the first ever census of dust attenuation in disc galaxies as a simultaneous function of stellar mass, specific star formation rate, size and concentration. He finds that attenuation is a strong function of all parameters, but especially specific star formation rate and size. Because specific star formation rate and stellar mass are expected to control the stellar populations (through the star formation history and metallicity of galaxies), he can use the intercept of the color-inclination relation as a function of structural parameters to explore the effects of face-on dust. Simple scaling relation-based models in which dust optical depth scales only with gas density and metallicity, coupled with published radiative transfer simulations, reproduce the observed patterns in relative attenuation and face-on color with startling accuracy.

Congratulations, Brian!