The Sloan Digital Sky Survey Quasar Lens Search. VI. Constraints on Dark
  Energy and the Evolution of Massive Galaxies
  We present a statistical analysis of the final lens sample from the Sloan
Digital Sky Survey Quasar Lens Search (SQLS). The number distribution of a
complete subsample of 19 lensed quasars selected from 50,836 source quasars is
compared with theoretical expectations, with particular attention to the
selection function. Assuming that the velocity function of galaxies does not
evolve with redshift, the SQLS sample constrains the cosmological constant to
\Omega_\Lambda=0.79^{+0.06}_{-0.07}(stat.)^{+0.06}_{-0.06}(syst.) for a flat
universe. The dark energy equation of state is found to be consistent with w=-1
when the SQLS is combined with constraints from baryon acoustic oscillation
(BAO) measurements or results from the Wilkinson Microwave Anisotropy Probe
(WMAP). We also obtain simultaneous constraints on cosmological parameters and
redshift evolution of the galaxy velocity function, finding no evidence for
redshift evolution at z<1 in any combinations of constraints. For instance,
number density evolution quantified as \nu_n=d\ln\phi_*/d\ln(1+z) and the
velocity dispersion evolution \nu_\sigma=d\ln\sigma_*/d\ln(1+z) are constrained
to \nu_n=1.06^{+1.36}_{-1.39}(stat.)^{+0.33}_{-0.64}(syst.) and
\nu_\sigma=-0.05^{+0.19}_{-0.16}(stat.)^{+0.03}_{-0.03}(syst.) respectively
when the SQLS result is combined with BAO and WMAP for flat models with a
cosmological constant. We find that a significant amount of dark energy is
preferred even after fully marginalizing over the galaxy evolution parameters.
Thus the statistics of lensed quasars robustly confirm the accelerated cosmic
expansion.
