Cosmic evolution of dust in galaxies: methods and preliminary results.
Abstract (from CDS):
We investigate the redshift (z) evolution of dust mass and abundance, their dependences on initial conditions of galaxy formation, and physical correlations between dust, gas, and stellar contents at different z based on our original chemodynamical simulations of galaxy formation with dust growth and destruction. In this preliminary investigation, we first determine the reasonable ranges of the most important two parameters for dust evolution, i.e., the timescales of dust growth and destruction, by comparing the observed and simulated dust mass and abundances and molecular hydrogen (H2) content of the Galaxy. We then investigate the z-evolution of dust-to-gas ratios (D), H2 gas fraction (fH2), and gas-phase chemical abundances (e.g., AO= 12 + log (O/H)) in the simulated disk and dwarf galaxies. The principal results are as follows. Both D and fH2 can rapidly increase during the early dissipative formation of galactic disks (z ∼ 2-3), and the z-evolution of these depends on initial mass densities, spin parameters, and masses of galaxies. The observed AO-D relation can be qualitatively reproduced, but the simulated dispersion of D at a given AO is smaller. The simulated galaxies with larger total dust masses show larger H2and stellar masses and higher fH2. Disk galaxies show negative radial gradients of D and the gradients are steeper for more massive galaxies. The observed evolution of dust masses and dust-to-stellar-mass ratios between z = 0 and 0.4 cannot be reproduced so well by the simulated disks. Very extended dusty gaseous halos can be formed during hierarchical buildup of disk galaxies. Dust-to-metal ratios (i.e., dust-depletion levels) are different within a single galaxy and between different galaxies at different z.
dust, extinction - galaxies: evolution - galaxies: ISM