High-resolution panchromatic spectral models of galaxies including photoionization and dust

Abstract

An updated version of the dust radiation-transfer code sunrise, including models for star-forming regions and a self-consistent calculation of the spatially dependent dust and PAH emission, is presented. Given a hydrodynamic simulation of a galaxy, this model can calculate a realistic 2D ultraviolet–submillimetre spectral energy distribution of the galaxy, including emission lines from H ii regions, from any viewpoint. To model the emission from star-forming regions, the mappingsiii photoionization code is used. The high wavelength resolution (∼1000 wavelengths) is made possible by the polychromatic Monte Carlo algorithm employed by sunrise. From the 2D spectral energy distributions (SEDs), images in any filter bands or integrated galaxy SEDs can be created. Using a suite of hydrodynamic simulations of disc galaxies, the output broad-band images and SEDs are compared with observed galaxies from the multiwavelength SINGS and SLUGS galaxy surveys. Overall, the output SEDs show a good match with observed galaxies in colours ranging from far-UV to submillimetre wavelengths. The only possible exception is the 160/850 μm colour, which the simulations underestimate by a factor of ∼5 compared to the SINGS sample. However, the simulations here agree with the SLUGS galaxies, which consistently have significantly larger amounts of cold dust than the SINGS galaxies. The sunrise model can be used to generate simulated observations of arbitrary hydrodynamic galaxy simulations. In this way, predictions of galaxy formation theories can be directly tested against observations of galaxies.