Unveiling the dark side of the Universe: probing dark matter and energy with cluster lensing

“Gravitational lensing, the bending of light beams in the Universe is a prediction of General Relativity. This phenomenon causes the shapes of distant background galaxies to be  distorted due to the presence of foreground mass concentrations in the Universe. Recent inventories of the Universe suggest that the budget is dominated by dark energy and dark matter with ordinary atoms contributing a paltry 5%. Dark energy is believed to be powering the accelerating expansion of the Universe. Dark matter on the other hand is believed to be composed of  exotic particles that were likely created in the very early Universe. It turns out that the contents, geometry and the fate of the Universe are intricately linked. Clusters of galaxies, the  largest repositories of dark matter in the Universe, cause the most  dramatic lensing  effects which are detected with the exquisite optics of the Hubble Space Telescope. Gravitational lensing by clusters has emerged as a powerful cosmological probe, enabling mapping of dark matter and constraining dark energy. I will present lensing tests of some of the key aspects of the cold dark matter paradigm that offers insights into the nature of dark matter. Cluster strong lensing can also be used to constrain dark energy. I will present  new results of application of this technique to probe the geometry of the Universe.”