Strong Gravitational Lensing and Dark Energy

Abstract

We investigate the statistics of gravitational lenses in flat, low-density cosmological models with different cosmic equations of state ω. We compute the lensing probabilities as a function of image separation θ using a lens population described by the mass function of Jenkins et al. and modeled as singular isothermal spheres on galactic scales and as Navarro, Frenk, and White halos on cluster scales. It is found that COBE -normalized models with ω > -0.4 produce too few arcsecond-scale lenses in comparison with the Jodrell-VLA Astrometric Survey (JVAS) and the Cosmic Lens All-Sky Survey (CLASS), a result that is consistent with other observational constraints on ω. The wide-separation (θ ##IMG## [http://ej.iop.org/icons/Entities/gtrsim.gif] {gtrsim} 4'') lensing rate is a particularly sensitive probe of both ω and the halo mass concentration. The absence of these systems in the current JVAS/CLASS data excludes highly concentrated halos in ω ##IMG## [http://ej.iop.org/icons/Entities/lesssim.gif] {lesssim} -0.7 models. The constraints can be improved by ongoing and future lensing surveys of greater than 10 5 sources.