Star formation in local interacting galaxies: A tale of compactness
Rafael Martinez Galarza (CfA, Harvard)
May 12, 2014
Abstract: At intermediate redshifts, a correlation has been found by some authors (i.e. Magnelli et al., 2013) between the dust temperature in star-forming galaxies, their specific star formation rate, and their distance from the so-called main sequence (MS) in the SFR-M? plane. This result has been interpreted in terms of a difference in the ISM physics between galaxies on and off the MS. By combining hydrodynamical simulations, state-of-the-art radiative transfer models and real observations, in this talk I propose a characterization of the ISM physics in local interacting systems in terms of the compactness parameter, which is related to the average heating flux irradiated onto the dust particles surrounding indiviudal HII regions. I present CHIBURST, a Monte Carlo Bayesian algorithm to fit the multiwavelength SEDs of a set of hydrodynamical simulations and observed nearby interactions. I will show that compactness correlates with the specific SFR (sSFR) in both simulations and observations and I will provide some possible physical interpretations for this correlation. As a bonus, I will show that MS galaxies show on average smaller compactness values as compared to their starburst counterparts. This link between the overall SED properties of starbursts and the internal physics of the ISM at the HII region level is a promising tool in the characterization of unresolved starbursts, and points to a physically based definition of the MS of star formation in galaxies.