Cosmography using strongly lensed gravitational waves from binary black holes

TL;DR

This paper proposes a Bayesian method to use strongly lensed gravitational waves from binary black hole mergers to estimate cosmological parameters, offering a new probe of high-redshift universe ($z \,\sim\, 10$).

Contribution

It introduces a novel Bayesian analysis framework for cosmology using lensed GW events, focusing on the number and time delay distribution of lensed signals.

Findings

Constraints comparable to other cosmological probes.

Probes a high redshift regime ($z \sim 10$).

Method applicable to future GW detector data.

Abstract

Third generation gravitational wave (GW) detectors are expected to detect millions of binary black hole (BBH) mergers during their operation period. A small fraction of them ($\sim 1\%$) will be strongly lensed by intervening galaxies and clusters, producing multiple observable copies of the GW signals. The expected number of lensed events and the distribution of the time delay between lensed events depend on the cosmology. We develop a Bayesian analysis method for estimating cosmological parameters from the detected number of lensed events and their time delay distribution. The expected constraints are comparable to that obtained from other cosmological measurements, but probing a different redshift regime ($z \sim 10$) that is not explored by other probes.