Cosmic Constraints to wCDM Model from Strong Gravitational Lensing

TL;DR

This study uses strong gravitational lensing data from multiple surveys to constrain the wCDM cosmological model, comparing two lensing models and analyzing their impact on parameter estimation.

Contribution

It introduces a comparative analysis of SIS and PLP lensing models for cosmological constraints using a large lensing dataset, highlighting the influence of model choice on parameter estimates.

Findings

PLP model provides tighter constraints than SIS.

Cosmological parameters are insensitive to the power-law index.

Discrepancies with Planck results may stem from systematic errors.

Abstract

In this paper, we study the cosmic constraint to $w$CDM model via $118$ strong gravitational lensing systems which are complied from SLACS, BELLS, LSD and SL2S surveys, where the ratio between two angular diameter distances $D^{obs} = D_A(z_l,z_s)/D_A(0,z_s)$ is taken as a cosmic observable. To obtain this ratio, we adopt two strong lensing models: one is the singular isothermal sphere model (SIS), the other one is the power-law density profile (PLP) model. Via the Markov Chain Mote 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 relative tighter constraint to the cosmological parameters than that of the SIS model. The predicted value of $\Omega_m=0.31^{+0.44}_{-0.24}$ by SIS model is compatible with that obtained by {\it Planck}2015: $\Omega_{m}=0.313\pm0.013$. However, the value of $\Omega_m=0.15^{+0.13}_{-0.11}$ based on the PLP model is smaller and has $1.25\sigma$ tension with that obtained by {\it Planck}2015 result. This discrepancy maybe come from the systematic errors.