Cosmological Parameter Estimation Using Current and Future Observations of Strong Gravitational Lensing

TL;DR

This paper evaluates the potential of strong gravitational lensing observations, including velocity dispersions and time delays, to improve constraints on cosmological parameters, especially with future large surveys like LSST.

Contribution

It combines current SGL data with simulations of future observations to demonstrate the potential of SGL in breaking parameter degeneracies and achieving precision cosmology.

Findings

Current SGL data do not significantly break parameter degeneracies.

Future SGL observations can greatly improve parameter constraints.

SGL will become a valuable late-universe probe for cosmology.

Abstract

Remarkable development of cosmology is benefited from the increasingly improved measurements of cosmic distances including absolute distances and relative distances. In recent years, however, the emerged cosmological tensions motivate us to explore the independent and precise late-universe probes. The two observational effects of strong gravitational lensing (SGL), the velocity dispersions of lens galaxies and the time delays between multiple images, can provide measurements of relative and absolute distances respectively, and their combination is possible to break the degeneracies between cosmological parameters and enable tight constraints on cosmological parameters. In this paper, we combine the observed 130 SGL systems with velocity-dispersion measurements and 7 SGL systems with time-delay measurements to constrain dark-energy cosmological models. It is found that the combination of the two effects does not significantly break the degeneracies between cosmological parameters as expected. However, with the simulations of 8000 SGL systems with well-measured velocity dispersions and 55 SGL systems with well-measured time delays based on the forthcoming LSST survey, we find that the combination of two effects can significantly break the parameter degeneracies, and make the constraint precision of cosmological parameters meet the standard of precision cosmology. We conclude that the observations of SGL will become a useful late-universe probe for precisely measuring cosmological parameters.