Modeling IR Spectral Energy Distributions: A Pilot Study of Starburst Parameters and Silicate Absorption Curves for Some GOALS Galaxies

• Published in: arXiv.org
• Main Authors: Dopita, Michael A, Armus, Lee, Kewley, Lisa J, Rich, Jeff A, Sanders, Dave, Appleton, Phillip N, Chan, Ben H P, Charmandaris, Vassilis, Evans, Aaron S, Frayer, David T, Howell, Justin H, Inami, Hanae, Mazzarella, Joseph A, Petric, Andreea, Stierwalt, Sabrina, Surace, Jason
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 10.12.2010
• Subjects: Absorption; Active galactic nuclei; Celestial bodies; Empirical analysis; Extinction; Galaxies; Galaxy distribution; Interstellar matter; Mathematical models; Observatories; Organic chemistry; Parameter robustness; Parameter sensitivity; Physical properties; Physics - Cosmology and Nongalactic Astrophysics; Sky surveys (astronomy); Space telescopes; Spectra; Spectral energy distribution; Star & galaxy formation; Star formation rate
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1012.2174

This paper describes a pilot study into the spectral energy distribution (SED) fitting and the derivation of physical parameters for 19 galaxies observed as part of the Great Observatories All-sky LIRG Survey (GOALS) survey as observed with the \emph{Spitzer Space Telescope}. For this we have used the pan-spectral fitting tools developed in a series of papers by Dopita and his co-workers. We show that the standard Lee and Draine `astronomical silicate' model cannot provide a good fit to the silicate absorption features as observed in the heavily dust-extinguished (\(A_{\rm V} \sim 50\)mag.) starbursts. We have derived an empirical fit to the `starburst silicate' absorption in these objects. This absorption curve is consistent with the silicate grains being systematically larger in starburst environments than in the local Galactic interstellar medium. We demonstrate the sensitivity of the SED fitting to each of the fitted parameters, and derive these parameters for those galaxies which do not have an embedded AGN. This technique is simple and provides reasonably robust and uniform parameters for the starburst, especially as far as the star formation rate, population of old stars, compactness of the starburst region and total foreground extinction are concerned. However, the chemical abundances and the optical extinction cannot be reliably determined by this analysis, and optical SEDs will also be required to provide a complete characterization of the starburst region and of the surrounding galaxy.