Abstract

We present cosmological results from the statistics of lensed quasars in the Sloan Digital Sky Survey (SDSS) Quasar Lens Search. By taking proper account of the selection function, we compute the expected number of quasars lensed by early-type galaxies and their image separation distribution assuming a flat universe, which is then compared with seven lenses found in the SDSS Data Release 3 to derive constraints on dark energy under strictly controlled criteria. For a cosmological constant model (w = -1) we obtain ΩΛ = 0.74+0.11 -0.15(stat.) +0.13 -0.06(syst.). Allowing w to be a free parameter we find ΩM = 0.26+0.07 -0.06(stat.) +0.03 -0.05(syst.) and w = -1.1 0.6(stat.)+0.3 -0.5(syst.) when combined with the constraint from the measurement of baryon acoustic oscillations in the SDSS luminous red galaxy sample. Our results are in good agreement with earlier lensing constraints obtained using radio lenses, and provide additional confirmation of the presence of dark energy consistent with a cosmological constant, derived independently of type Ia supernovae. © 2008. The American Astronomical Society. All rights reserved.