Metal and Dust Build-up in the Universe: Constraints from Lyman-Break Galaxies at the Epoch of Reionization

We discuss the constraints on the physical processes regulating the baryon cycle in Lyman-Break galaxies at the epoch of reionization (5< z <10) and in local dwarf galaxies, often considered to be the local counterparts of the former in terms of physical properties. Specifically, we constrain: a) the relative contribution of Supernovae (SNe) and of thermally pulsing asymptotic giant branch (TP-AGB) stars to the chemical enrichment of galaxies, b) the dust destruction efficiency operated by SN shocks in the interstellar medium (ISM), c) the dust growth in the ISM, d) the efficiency of conversion of gas into stars, e) the efficiency of galactic outflows in removing dust and gas from the ISM. We find that fast enrichment in metals and dust from Type II SNe followed by dust removal through galactic outflows is required to reproduce the observations, while destruction of dust by SN shocks has limited efficiency. The fast enrichment from Type II SNe is obtained assuming a top-heavy initial mass function for stars and a condensation fraction of dust of ⪆ 50.