Global Evolution Models and the Extragalactic Background Light

This article outlines a method to interpret the extragalactic background light in terms of the large-scale, average properties of galaxies, including the comoving densities of stars and interstellar gas, metals, and dust. These quantities are related by a series of coupled conservation-type equations analogous to the equations of galactic chemical evolution. This approach enables us to combine observations of the emission and absorption in galaxies and thus to relate their average stellar and interstellar contents. Applications of the method include predictions of the global history of star formation from absorption-line observations and corrections to the cosmic UV emissivity for absorption by dust.