Speaker
Priyamvada Natarajan
Description
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 (DE) equation of state.
Combining our cosmological constraints with those from X-ray
clusters and the Wilkinson Microwave Anisotropy Probe 5-year
data, we find that dark matter comprises a fraction Omega_m
= 0.25 +/- 0.05 of critical density and that the DE
parameter wx = -0.97 +/- 0.07, both consistent with results
from other methods. Inclusion of our method with all other
techniques available brings down the current 2- sigma
contours on the dark energy equation of state parameter wx
by about 30%.
