Cosmology with Strong Lensing Systems

TL;DR

This paper compiles a large catalog of strong gravitational lensing systems to constrain dark energy models and cosmic parameters, demonstrating the potential of lensing data to probe the universe's expansion and dark energy evolution.

Contribution

It introduces a comprehensive analysis of 118 lensing systems with flexible mass models, improving constraints on dark energy parameters and their evolution over redshift.

Findings

Constraints on dark energy parameters are consistent with previous studies.

Lensing data provides complementary information to supernova observations.

Results suggest potential evolution of the cosmic equation of state with redshift.

Abstract

In this paper, we assemble a catalog of 118 strong gravitational lensing systems from SLACS, BELLS, LSD and SL2S surveys and use them to constrain the cosmic equation of state. In particular we consider two cases of dark energy phenomenology: $XCDM$ model where dark energy is modeled by a fluid with constant $w$ equation of state parameter and in Chevalier - Polarski - Linder (CPL) parametrization where $w$ is allowed to evolve with redshift: $w(z) = w_0 + w_1 \frac{z}{1+z}$. We assume spherically symmetric mass distribution in lensing galaxies, but relax the rigid assumption of SIS model in favor to more general power-law index $\gamma$, also allowing it to evolve with redshifts $\gamma(z)$. Our results for the $XCDM$ cosmology show the agreement with values (concerning both $w$ and $\gamma$ parameters) obtained by other authors. We go further and constrain the CPL parameters jointly with $\gamma(z)$. The resulting confidence regions for the parameters are much better than those obtained with a similar method in the past. They are also showing a trend of being complementary to the supernova Ia data. Our analysis demonstrates that strong gravitational lensing systems can be used to probe cosmological parameters like the cosmic equation of state for dark energy. Moreover, they have a potential to judge whether the cosmic equation of state evolved with time or not.