Can we constrain galaxy geometry parameters using spatially integrated SED fitting?

Abstract

ABSTRACT Sophisticated spectral energy distribution (SED) models describe dust attenuation and emission using geometry parameters. This treatment is natural since dust effects are driven by the underlying star–dust geometry in galaxies. An example is the starduster SED model, which divides a galaxy into a stellar disc, a stellar bulge, and a dust disc. This work utilizes the starduster SED model to study the efficacy of inferring geometry parameters using spatially integrated SED fitting. Our method fits the SED model to mock photometry produced by combining a semi-analytic model with the same SED model. Our fitting results imply that the disc radius can be constrained, while the inclination angle, dust disc to stellar disc radius ratio, bulge radius, and intrinsic bulge to total luminosity ratio are unconstrained, even though 21 filters from ultraviolet to far-infrared are used. We also study the impact of signal-to-noise (S/N) ratio, finding that the increase of S/N (up to 80) brings limited improvements to the results. We provide a detailed discussion to explain these findings, and point out the implications for models with more general geometry.