Quasar Absorption-Line Number Density in a Closed, Λ-Dominated Universe

Abstract

We investigate the dependence of the line number density in the Lyman α forest on cosmological and evolutionary parameters. Recent data from eight high-redshift quasars obtained with VLT/UVES imply that either there is very strong evolution in the absorber population, or we live in a "nearly flat" closed universe which is more heavily vacuum-dominated than standard CDM models.