Cosmology Seminar Announcement Dr. Jochen Weller Fermilab " Constraining Dark Energy with X-ray Galaxy Clusters, Supernovae and the Cosmic Microwave Background " Date: Thursday, April 21, 2005 416 Phy/Geo Time: 12:10 pm. Abstract: We present new constraints on the evolution of dark energy from an analysis of Cosmic Microwave Background, supernova and X-ray galaxy cluster data. Our analysis employs a minimum of priors and exploits the complementary nature of these data sets. We examine a series of dark energy models with up to three free parameters: the current dark energy equation of state $w_{\rm 0}$, the early time equation of state $w_{\rm et}$ and the scale factor at transition, $a_{\rmt}$. We find no significant evidence for evolution in the dark energy equation of state parameter with redshift. Marginal hints of evolution in the supernovae data become less significant when the cluster constraints are also included in the analysis. The complementary nature of the ata sets leads to a tight constraint on the mean matter density, $\Omega_{\rm m}$ and alleviates a number of other parameter degeneracies, including that between the scalar spectral index $n_{\rm s}$, the physical baryon density $\Omega_{\rm b}h2$ and the optical depth $\tau$. This complementary nature also allows us to examine models in which we drop the prior on the curvature.

E-Mail: jweller@fnal.gov
Web Page: http://home.fnal.gov/~jweller/