Constraining Dark Energy From Splitting Angle Statistic of Strong Gravitational Lenses

Qing-Jun Zhang; Ling-Mei Cheng; Yue-Liang Wu

doi:10.1088/0004-637X/694/2/1402

paper

Constraining Dark Energy From Splitting Angle Statistic of Strong Gravitational Lenses

arXiv:0708.2164 · doi:10.1088/0004-637X/694/2/1402

Abstract

Utilizing the CLASS statistical sample, we investigate the constraint of the splitting angle statistic of strong gravitational lenses(SGL) on the equation-of-state parameter $w = p / ρ$ of the dark energy in the flat cold dark matter cosmology. Through the comoving number density of dark halos described by Press-Schechter theory, dark energy affects the efficiency with which dark-matter concentrations produce strong lensing signals. The constraints on both constant $w$ and time-varying $w (z) = w_{0} + w_{a} z / (1 + z)$ from the SGL splitting angle statistic are consistently obtained by adopting a two model combined mechanism of dark halo density profile matched at the mass scale $M_{c}$ . Our main observations are: (a) the resulting model parameter $M_{c}$ is found to be $M_{c} \sim 1.4$ for both constant $w$ and time-varying $w (z)$ , which is larger than $M_{c} \sim 1$ obtained in literatures; (b) the fitting results for the constant $w$ are found to be $w = - 0.8 9_{- 0.26}^{+ 0.49}$ and $w = - 0.9 4_{- 0.16}^{+ 0.57}$ for the source redshift distributions of the Gaussian models $g (z_{s})$ and $g^{c} (z_{s})$ respectively, which are consistent with the $Λ CDM$ at 95% C.L; (c) the time-varying $w (z)$ is found to be for $σ_{8} = 0.74$ : $(M_{c}; w_{0}, w_{a}) = (1.36; - 0.92, - 1.31)$ and $(M_{c}; w_{0}, w_{a}) = (1.38; - 0.89, - 1.21)$ for $g (z_{s})$ and $g^{c} (z_{s})$ respectively.

30 pages, 10 figures, references added, improved version to be published in ApJ

Constraining Dark Energy From Splitting Angle Statistic of Strong Gravitational Lenses

Abstract

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