Constraints on dark energy from baryon acoustic peak and galaxy cluster gas mass measurements

We use baryon acoustic peak measurements by Eisenstein et al. (2005) and Percival et al. (2007a), together with the WMAP measurement of the apparent acoustic horizon angle, and galaxy cluster gas mass fraction measurements of Allen et al. (2008), to constrain a slowly rolling scalar field dark energy model, φCDM, in which dark energy’s energy density changes in time. We also compare our φCDM results with those derived for two more common dark energy models: the time-independent cosmological constant model, ΛCDM, and the XCDM parametrization of dark energy’s equation of state. For time-independent dark energy, the Percival et al. (2007a) measurements effectively constrain spatial curvature and favor a close to spatially-flat model, mostly due to the WMAP CMB prior used in the analysis. In a spatially-flat model the Percival et al. (2007a) data less effectively constrain time-varying dark energy. The joint baryon acoustic peak and galaxy cluster gas mass constraints on φCDM model are consistent with but tighter than those derived from other data. A time-independent cosmological constant in a spatially-flat model provides a good fit to the joint data, while the α parameter in the inverse power law potential φCDM model is constrained to be less than about 4 at 3σ confidence level. Subject headings: cosmological parameters — distance scale — large-scale structure of universe— X-rays: galaxies: clusters Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, KS 66506, [email protected], [email protected]. National Abastumani Astrophysical Observatory, 2A Kazbegi Ave, GE-0160 Tbilisi, Georgia