Theoretical clues about dust accumulation and galaxy obscuration at high and low redshift

Abstract

ABSTRACT Since the epoch of cosmic star formation peaks at z ∼ 2, most of it is obscured in high-mass galaxies, while in low-mass galaxies, the radiation escapes unobstructed. During the reionization epoch, the presence of evolved, dust obscured galaxies are a challenge to galaxy formation and evolution models. By means of a chemodynamical evolution model, we investigate the star formation and dust production required to build up the bulk of dust in galaxies with initial baryonic mass ranging from 7.5 × 107 to 2.0 × 1012 M⊙. The star formation efficiency was also chosen to represent the star formation rate (SFR) from irregular dwarf to giant elliptical galaxies. We adopted a dust coagulation efficiency from Dwek (Case A) as well as a lower efficiency one (Case B), about five times smaller than Case A. All possible combination of these parameters was computed, summing 40 different scenarios. We find that in high stellar formation systems, the dust accretion in interstellar medium rules over stellar production before the star formation peak, making these systems almost insensible to dust coagulation efficiency. In low star formation systems, the difference between Case A and B lasts longer, mainly in small galaxies. Thus, small irregular galaxies should be the best place to discriminate different dust sources. In our observational sample, taken from the literature, the dust-to-gas ratio tends to be more spread only than dust mass, for both stellar mass and SFR. The dust-to-gas versus dust-to-star diagram is a good tracer for both galaxy and dust evolution, due to the link between gas, star, dust, and SFR. However, the model do not constrain simultaneously all this quantities. The new generation facilities (such as James Webb Space Telescope, Extremely Large Telescope, GMT, and SPICA) will be indispensable to constrain dust formation across the cosmic time.