Analysis of galaxy SEDs from far-UV to far-IR with CIGALE: Studying a SINGS test sample

Abstract

Photometric data of galaxies covering the rest-frame wavelength range from far-UV to far-IR make it possible to derive galaxy properties with a high reliability by fitting the attenuated stellar emission and the related dust emission at the same time. For this purpose we wrote the code CIGALE (Code Investigating GALaxy Emission) that uses model spectra composed of the Maraston (or PEGASE) stellar population models, synthetic attenuation functions based on a modified Calzetti law, spectral line templates, the Dale & Helou dust emission models, and optional spectral templates of obscured AGN. Depending on the input redshifts, filter fluxes are computed for the model set and compared to the galaxy photometry by carrying out a Bayesian-like analysis. CIGALE was tested by analysing 39 nearby galaxies selected from SINGS. The reliability of the different model parameters was evaluated by studying the resulting expectation values and their standard deviations in relation to the input model grid. Moreover, the influence of the filter set and the quality of photometric data on the code results was estimated. For up to 17 filters between 0.15 and 160 mum, we find robust results for the mass, star formation rate, effective age of the stellar population at 4000 A, bolometric luminosity, luminosity absorbed by dust, and attenuation in the far-UV. A study of the mutual relations between the reliable properties confirms the dependence of star formation activity on morphology in the local Universe and indicates a significant drop in this activity at about 10^11 M_sol towards higher total stellar masses. The dustiest sample galaxies are present in the same mass range. [abridged]