Coevolution of dust, gas, and stars in galaxies - I. Spatial distributions and scaling-relations of dust and molecular hydrogen

Abstract

We investigate the time evolution of dust properties, molecular hydrogen (H_2) contents, and star formation histories in galaxies by using our original chemodynamical simulations. The simulations include the formation of dust in the stellar winds of supernovae (SNe) and asymptotic giant branch (AGB) stars, the growth and destruction processes of dust in the interstellar medium (ISM), the formation of polycyclic aromatic hydrocarbon (PAH) dust in carbon-rich AGB stars, the H_2 formation on dust grains, and the H_2 photo-dissociation due to far ultra-violet (FUV) light in a self-consistent manner. We focus mainly on disk galaxies with different total masses in this preliminary study. The principle results are as follows: The star formation histories of disk galaxies can be regulated by the time evolution of interstellar dust, mainly because the formation rates of H_2 can be controlled by dust properties. The observed correlation between dust-to-gas-ratios (D) and gas-phase oxygen abundances (A_O = 12+log(O/H)) can be reproduced reasonably well in the present models. The disks show negative radial gradients (i.e., larger in inner regions) of H_2 fraction (f_H2), PAH-to-dust mass ratio (f_PAH), D, and A_O and these gradients evolve with time. The surface-mass densities of dust (Sigma_dust) are correlated more strongly with the total surface gas densities than with those of H_2. Local gaseous regions with higher D are more likely to have higher f_H2 in individual disks and total H_2 masses correlate well with total dust masses. More massive disk galaxies are more likely to have higher D, f_PAH, and f_H2 and smaller dust-to-stellar mass ratios. We also compare between galactic star formation histories in the metallicity-dependent and dust-dependent star formation models and find no major differences.