Cosmological Constraints from Strong Gravitational Lensing in Clusters of Galaxies

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. Exploiting high resolution images from the Advanced Camera for Surveys aboard the Hubble Space Telescope and extensive ground-based spectroscopic follow-up of the massive galaxy clus-ter 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 Mi-crowave Anisotropy Probe 5-year data gives Ωm = 0.25±0.05 and wx = −0.97± 1 0.07 which is extremely competitive with other methods. Inclusion of our method with all other techniques available brings down the current 2σ con-tours on the dark energy equation of state parameter wx by about 30%. Measurements of the Hubble diagram for Type Ia supernovae (1–4) combined with con-straints from the Wilkinson Microwave Anisotropy Probe (WMAP5) (5,6), cosmic shear obser