CfA OIR Division Lunch Talks
Wednesday, October 17, 2012, 11:00 am, Pratt Conference Room

Bayesian Fitting of Starburst Spectra:
Spitzer, Herschel and Beyond

Juan Rafael Martinez Galarza (CfA)

The Spectral Energy Distributions (SEDs) of star-forming regions and starburst galaxies are unique tracers of the star formation processes in these environments, since they contain information on the escaping and processed photons emitted by newly formed massive stars. Understanding these internal processes is crucial in our interpretation of observations of unresolved star formation in the Universe. I present a novel Bayesian routine to fit the multi-wavelength spectra of starbursts. The method finds robust fits to the observed mid-and far-infrared SEDs of these objects, starting from a grid of state-of-the-art, panchromatic, radiative transfer and dynamical SED models. We find statistically meaningful constrains to model parameters such as starburst age, fraction of photon-dominated regions to HII regions and star formation rates. By applying this fitting routine to multi-wavelength spectral and photometric data of the giant HII regions 30 Doradus and NGC 604, including Spitzer and Herschel observations, I show that the inclusion of the fine-structure emission lines in the fitting is crucial to break the degeneracies between model parameters, and discuss the new astrophysics that arise from this analysis, emphasizing on the content of embedded star formation currently taking place in these regions, which I independently quantify using the method. I will show that the fitting routine is an excellent tool in the analysis of the spectral properties of unresolved galaxies, and discuss some early results on applying the method to nearby starbursts.