Dust across galaxies

In this thesis, we investigate the evolution of dust mass and chemical composition in different galaxies by means of new detailed chemical evolution models which account for the presence of dust. We adopt updated prescriptions for dust formation in Asymptotic Giant Branch (AGB) stars and Type II SNe, as well as for dust accretion and destruction in the interstellar medium (ISM). We predict in detail the evolution of the abundances of single elements both in the dust and in gas phase of the ISM, and distinguish the contributions from different sources during the galactic time. We study the dust evolution in galaxies of different morphological type, i.e. dwarf irregulars, spirals, Milky Way-type and ellipticals: our model has proven to be very useful to study various dust properties such as dust mass, dust-to-gas (DG) ratio and chemical composition. In our approach, the main difference between galaxies is the star formation history: in ellipticals it is assumed a very fast and intense star formation rate, and this rate decreases going towards spirals, irregulars and smaller galaxies. First, we compare our model predictions for a typical dwarf irregular galaxy with chemical abundances measured in Damped Lyman Alpha (DLA) systems. After having reproduced the abundances of volatile elements S and Zn (unaffected by the presence of dust), we study the depletion patterns of refractory elements (Si and Fe), which tend to be incorporated in the dust phase. Our study suggests that Fe and Si undergo a different history of dust formation and evolution and that Fe is mainly incorporated into iron-rich solid nano-particles, which may form by dust growth in the ISM. We also provide a new method, based on DLA column density measurements and the ratio between volatile and refractory elements, to give for the first time an estimate of the chemical abundance ratios inside dust grains. In this way, we try to disentangle the main dust constituents and predict their evolution: in particular, we focus on the fraction between silicates and metallic particles and between pyroxenes and olivines. Concerning the Milky Way, we present the evolution (in space and time) of the DG ratio in the context of the galactic habitable zone, defined as the region with highly enough metallicity to form planetary systems capable of sustaining life. In this study, we provide theoretical prescriptions of the DG ratio and metallicity for models of planetary systems formation. Then we focus our study on high redshift elliptical galaxies, and we try to disentangle the responsible processes for the sudden appearance of metals and dust observed in those objects. The first metals and dust appear very early since they are both produced by short living massive stars (core-collapse SNe), on the time-scales of few tenths of million years. In their initial burst of star formation, the metallicity can attain almost a solar value after one hundred million years and the same is true for dust, to which also AGB stars contribute on time-scales equal or larger than 30 million years. Finally, we study the cosmic dust rate (CDR) across the Universe by assuming that the cosmic dust abundance results from the contribution of galaxies of different morphological type averaged in a unitary volume of the Universe. These galaxies are assumed to evolve in number density according to their weight in the luminosity function at different redshifts and different cosmological scenarios. Parallel to the CDR we compute the cosmic star formation rate (CSFR) as well as the cosmic rate of metallicity. Our predictions are extreme important to understand the roles of dust production, accretion and destruction in the CDR evolution. Our best scenario predicts a dust rate peak between 2<z<3 and reproduces the observed CSFR. Eventually, we estimate the comoving dust density parameter Ωdust and we find a good agreement with data for z<0.5.