Dusty Radiative Transfer Modeling of the Ultraviolet to Infrared Spectral Energy Distributions of Nearby Galaxies
Law, Ka Hei
MetadataShow full item record
In normal star forming galaxies without active galactic nuclei, stars and dust dominate the energy output in the ultraviolet (UV), optical and infrared (IR). Knowledge of stellar populations and dust is crucial to understanding the evolution of galaxies in the universe. The problems of dust and stars are tightly related because dust absorbs stellar radiation in the UV and optical, and re-radiates it in the IR. To study the properties of interstellar dust and stellar populations, we fit the global spectral energy distributions (SEDs) of nearby galaxies using radiative transfer models. Thanks to various space missions in the last few decades, the data required to construct the full UV to IR SEDs of nearby galaxies is available. To date, systematic studies on interstellar dust and stellar populations rely on simplified connections between the UV and IR such as energy conservation. Based on dust grain physics, radiative transfer models physically couple the UV and IR for consistent radiation fields and dust emission spectra, but is computationally challenging. With the use of supercomputer facilities, we compute a large grid of radiative transfer models spanning the physical range of dust and stellar parameters. Fitting SEDs with the grid is one step towards a better understanding of interstellar dust and stellar populations. By fitting the SEDs of a group of nearby galaxies observed by the SINGS survey, we study the relative importance of young and old stellar populations in heating the dust, derive the ensemble properties of dust, estimate the total mass of dust, and test the robustness of the various star formation rate indicators in the literature.