Yuan-Ming Hsu (ASIAA/NTU); Hiroyuki Hirashita (ASIAA); Yen-Hsing Lin (NTHU)
Dust emission from high-redshift galaxies gives us a clue to the origin and evolution of dust in the Universe. Previous studies have shown that different sources of dust (stellar dust production and dust growth in dense clouds) predict different ultraviolet--optical extinction curves for galaxies at z~7 but that the observed attenuation curves depend strongly on the geometry of dust and star distributions. Thus, we perform radiation transfer calculations using SKIRT under the geometries of dust and stars calculated by a cosmological hydrodynamic simulation (IllustrisTNG). This serves to investigate the dust attenuation curves predicted from 'realistic' geometries. We choose objects with stellar mass and star formation rate appropriate for Lyman break galaxies. We find that the attenuation curves are very different from the original extinction curves even in 'realistic' geometries. This makes it difficult to distinguish the dominant dust sources from the observed attenuation curves. We further include infrared dust emission in the analysis and plot the infrared excess (IRX)--ultraviolet SED slope (ß) diagram. We find that different sources of dust cause different IRX--ß relations for the simulated galaxies. We also show that the attenuation properties depends strongly on the dust-to-metal ratio. Thus, the comprehensive analysis of the abundances of dust and metals, the UV slope, and the dust emission could provide a clue to the dominant dust sources in the Universe.