Cosmic Constraints to the $w$CDM Model from Strong Gravitational Lensing
Jie An1, Bao-Rong Chang1, Li-Xin Xu1,2**
1Institute of Theoretical Physics, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 2State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190
Abstract：We study the cosmic constraint to the $w$CDM (cold dark matter with a constant equation of state $w$) model via 118 strong gravitational lensing systems which are compiled from SLACS, BELLS, LSD and SL2S surveys, where the ratio between two angular diameter distances $D^{\rm obs}=D_{\rm A}(z_{\rm l},z_{\rm s})/D_{\rm A}(0,z_{\rm s})$ is taken as a cosmic observable. To obtain this ratio, we adopt two strong lensing models: one is the singular isothermal sphere model (SIS) and the other one is the power-law density profile (PLP) model. Via the Markov chain Monte Carlo method, the posterior distribution of the cosmological model parameters space is obtained. The results show that the cosmological model parameters are not sensitive to the parameterized forms of the power-law index $\gamma$. Furthermore, the PLP model gives a relatively tighter constraint to the cosmological parameters than that of the SIS model. The predicted value of ${\it \Omega}_{\rm m}=0.31^{+0.44}_{-0.24}$ by the SIS model is compatible with that obtained by Planck2015: ${\it \Omega}_{\rm m}=0.313\pm0.013$. However, the value of ${\it \Omega}_{\rm m}=0.15^{+0.13}_{-0.11}$ based on the PLP model is smaller and has $1.25\sigma$ tension with that obtained by Planck2015.
. [J]. 中国物理快报, 2016, 33(07): 79801-079801.
Jie An, Bao-Rong Chang, Li-Xin Xu. Cosmic Constraints to the $w$CDM Model from Strong Gravitational Lensing. Chin. Phys. Lett., 2016, 33(07): 79801-079801.
2016, Vol. 33 
