Cosmological Parameters from the SDSS DR5 Velocity Dispersion Function of Early-Type Galaxies through Radio-selected Lens Statistics

We improve strong lensing constraints on cosmological parameters in light ofthe new measurement of the velocity dispersion function of early-type galaxiesbased on the SDSS DR5 data and recent semi-analytical modeling of galaxyformation. Using both the number statistics of the CLASS statistical sample andthe image separation distribution of the CLASS and the PANELS radio-selectedlenses, we find the cosmological matter density $\Om = 0.25^{+0.12}_{-0.08}$(68% CL) assuming evolutions of galaxies predicted by a semi-analytical modelof galaxy formation and $\Om = 0.26^{+0.12}_{-0.08}$ assuming no evolution ofgalaxies for a flat cosmology with an Einstein cosmological constant. For aflat cosmology with a generalized dark energy, we find the non-evolving darkenergy equation of state $w_x < -1.2$ ($w_x < -0.5$) at the 68% CL (95% CL).Comment: ApJL, accepted (results and presentations revised; conclusions unchanged