The intergalactic medium (IGM) at redshifts around three is known to be enriched with heavy elements, but how and when these elements were produced and moved from galaxies into the IGM is a major open question in physical cosmology. This study will use high-resolution hydrodynamic simulations to analyze the absorption by carbon, silicon, oxygen, and nitrogen ions in a sample of high-quality quasar spectra covering redshifts two to five. This will yield metallicities, relative abundances, and their scatter, as a function of density and red shift, which will constrain the shape and evolution of the ultraviolet ionizing background radiation, the initial mass function, and the type of source responsible for the enrichment. Observed absorptions will be compared directly to realistic spectra from state-of-the-art cosmological simulations, both to test those simulations, and to constrain the effect of feedback on the IGM, the role of red shift-four galaxies in the enrichment of the IGM, and the allowed presence of metals in warm and hot gas.
As well as stringently testing cosmological simulations, the basis for a vast array of theoretical work, this research will develop broadly useful tools, train students, and afford ample opportunities for public talks and other educational outreach.
