COSMIC HISTORIES OF STARS, GAS, HEAVY ELEMENTS, AND DUST IN GALAXIES

摘要

We investigate a set of coupled equations that relates the stellar, gaseous, chemical, and radiation con-tents of the universe averaged over the whole population of galaxies. Using as input the available data from quasar absorption-line surveys, optical imaging and redshift surveys, and the COBE DIRBE and FIRAS extragalactic infrared background measurements, we obtain solutions for the cosmic histories of stars, interstellar gas, heavy elements, dust, and radiation from stars and dust in galaxies. Our solutions reproduce remarkably well a wide variety of observations that were not used as input. These include the integrated background light from galaxy counts from near-ultraviolet to near-infrared wavelengths, the rest-frame optical and near-infrared emissivities at various redshifts from surveys of galaxies, the mid-infrared and far-infrared emissivities of the local universe from the IRAS survey, the mean abundance of heavy elements at various epochs from surveys of damped Lya systems, and the global star formation rates at several redshifts from Ha mid-infrared, and submillimeter observations. The chemical enrichment history of the intergalactic medium implied by our models is also consistent with the observed mean metal content of Lya forest at high redshifts. We infer that the dust associated with star-forming regions is highly inhomogeneous and absorbs a significant fraction of the starlight, with only 41/100-46/100 of the total in the extragalactic optical background and the remaining 58/100-54/100 reprocessed by dust into the infrared background. The solutions pres