RSAA Colloquia / Seminars / Feast-of-Facts: Friday, 06 February 2015, 14:00-14:20; Duffield Lecture Theatre

Sarah Leslie

"A Radio-Optical Study of Resolved Star-Formation in Galaxies from the SAMI Galaxy Survey"

Our understanding of star formation in galaxies is facilitated by observations, at multiple wavelengths, of emission which traces stellar populations. Radio emission could provide an important extinction independent tracer, however the relationship radio emission (at 1.4 GHz) and star formation rate (SFR) is not well understood. Using optical integral field spectroscopy, my work aims to better understand the local SFR calibrations, which use H-alpha and radio continuum emission, when applied to different regions of a galaxy, as well as to galaxies as a whole. In our study of 13 radio-selected star-forming galaxies in the SAMI galaxy survey, we find that the radio continuum and H-alpha SFRs are consistent within galaxies which are not effected by shocks. We find that the ratio of SFR 1.4GHz /SFR H-alpha may be increased (by up to an order of magnitude) in the presence of shock excitation. Shocks from stellar winds and supernovae remnants may re-accelerate populations of cosmic rays, increasing the non-thermal radio emission and the SFR estimates.