Cosmography with strong lensing galaxy clusters (Eric Jullo - JPL/NASA)

Current efforts in observational cosmology are focused on characterizing the mass-energy content of the universe. We present results from a geometric test based on strong lensing in galaxy clusters.  Based on Hubble Space Telescope images and extensive ground-based spectroscopic follow-up of the massive galaxy cluster Abell 1689, we used a parametric model to simultaneously constrain the cluster mass distribution and dark energy equation of state. Combining our cosmological constraints with those from x-ray clusters and the Wilkinson Microwave Anisotropy Probe 5-year data gives Ωm = 0.25 +-0.05 and wx = -0.97 +-0.07, which are consistent with results from other methods. Inclusion of our method with all other available techniques  brings down the current 2scontours on the dark energy equation-of-state parameter wx by ~30%.