Constraints on dark energy from the lookback time versus redshift test

We use lookback time versus redshift data from galaxy clusters (Capozziello et al. 2004) and passively evolving galaxies (Simon et al. 2005), in combination with the WMAP determination of the age of the Universe, to constrain dark energy cosmological model parameters. Current lookback time data provide interesting and moderately restrictive constraints on cosmological parameters. When used jointly with current baryon acoustic peak and Type Ia supernovae apparent magnitude versus redshift data, lookback time data tighten the constraints on parameters and favor slightly larger values of the nonrelativistic matter energy density. Subject headings: cosmological parameters — galaxies: general — galaxies: clusters: general