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