Numerical simulations of the life cycle of dust in forming and evolving disk galaxies

Abstract

We present the first self-consistent numerical simulations of the time evolution of dust properties, molecular hydrogen (H2) contents, and star formation histories in forming disk gal axies. We focus mainly on the formation of disk galaxies with total masses ranging from 10 10 M⊙ to 10 12 M⊙ in a Cold Dark Matter (CDM) cosmology with the latest WMAP 7-year results. 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 formati on rates of H2 can be controlled by dust properties. More massive disk galaxies with higher stellar surface densities are likely to have smaller dust-to-star mass ratios (sd). The observed correlation between PAH-to-dust mass ratios (qPAH) and gas-phase oxygen abundances (AO ≡ 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 H2 fraction ( fH2 ), qPAH, dust-to-gas ratio (D), and AO and these gradients evolve with time. More massive disk galaxies are more likely to have higher D, qPAH, and fH2 . Early-type E/S0 galaxies formed by major galaxy merging can have lower sd than isolated late-type disk galaxies.