Constraints on cosmological models from lens redshift data
Abstract
Context. Stronglensing has developed into an important astrophysical tool for probing cosmology and galaxies (their structures, formations, and evolutions). Now several hundreds of stronglens systems produced by massive galaxies have been discovered, which may form welldefined samples useful for statistical analyses.
Aims: We aim to collect relatively complete lensredshift data from various large systematic surveys of gravitationally lensed quasars and check the possibility of using these as a future supplement to other cosmological probes.
Methods: We use the distribution of gravitationallylensed image separations observed in the Cosmic Lens AllSky Survey (CLASS), the PMNNVSS Extragalactic Lens Survey (PANELS), the Sloan Digital Sky Survey (SDSS) and other surveys, considering a singular isothermal ellipsoid (SIE) model for galactic potentials as well as improved new measurements of the velocity dispersion function of galaxies based on the SDSS DR5 data and recent semianalytical modeling of galaxy formation to constrain two darkenergy models (ΛCDM and constant w) under a flat universe assumption.
Results: We find that the current lensredshift data yield a relatively weak constraint on the model parameter Ω_{Λ} = 0.85_{0.18}^{+0.11} for the simplest cosmological constant model. However, by combing the redshift data with the cosmic macrowave background data, we obtain Ω_{Λ} = 0.78_{0.03}^{+0.02}; by combing the redshift data with the baryonic acoustic oscillation peak and the comic macrowave background data, we obtain a more stringent result: Ω_{Λ} = 0.75_{0.02}^{+0.02}. We obtain w < 0.52 at 68.3% CL with the lensredshift data for the constant w of a dynamical darkenergy model, therefore, the current quintessence darkenergy model is still included at 1σ and a supernegative equation of state is not necessarily favored by this strong lensing data. We notice that the joint data can also provide a good fit with Ω_{x} = 0.80_{0.17}^{+0.17}, w = 1.12_{1.88}^{+0.57} and Ω_{x} = 0.71_{0.07}^{+0.07}, w = 0.78_{0.34}^{+0.22}, respectively, which agree with the flat Λ CDM model at 1σ.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 February 2012
 DOI:
 10.1051/00046361/201015940
 arXiv:
 arXiv:1105.6182
 Bibcode:
 2012A&A...538A..43C
 Keywords:

 gravitational lensing: strong;
 cosmological parameters;
 dark energy;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 18 pages, 6 figures, 1 table, A&