Departament d'Astronomia i Astrofísica
Universitat de València

    Dark Energy and Cluster Lensing of Quasars

Ana Margarida Lopes

University of Oxford

Seminari del departament d'Astronomia i Astrofísica

Dijous 03 març 2005



The statistical study of strong gravitational lensing of quasars probes the number and evolution of dark matter halos in the Universe, offering a unique cosmological tool at the intermediate redshift regime, thus contrasting and complementing Cosmic Microwave Background measurements and galaxy clustering studies. The recent discovery of the first cluster lensed quasar SDSS J1004+4112, with a maximum image separation of 14.62 arcsec, breaks the long-standing 7 arcsec barrier and represents the discovery of a previously undetected population of lensed quasars. In this talk, I will present a new study of the frequency of cluster lensed quasars in universes dominated by dark energy using an analytical halo-based approach, and will demonstrate its sensitivity to critical assumptions about the lens properties and the cosmological model. I will discuss the extent to which observational surveys for cluster lensed quasars may be used to measure cosmological parameters such as the fractional matter density, the power spectrum normalisation, and the dark energy equation of state parameter. I will then report on our current observational effort to detect these systems. Finally, I will show how the predicted incidence of cluster lensed quasars will be tested against numerical simulations, taking into account elements like triaxiality and substructure in cluster lenses as well as the effect of multiple lensing agents.