Gravitational lensing aided luminosity distance estimation for compact binary coalescences

TL;DR

This paper shows that strong gravitational lensing can significantly improve the accuracy of luminosity distance measurements for compact binary coalescences detected by gravitational-wave observatories.

Contribution

It introduces a method to correctly estimate luminosity distances of lensed GW signals by leveraging the detection of multiple images from the same source.

Findings

Strong lensing can enhance distance estimation precision by up to a factor of a few.

Simulated GW signals from binary black holes demonstrate the effectiveness of the method.

Detection of multiple lensed signals allows for better parameter estimation.

Abstract

The luminosity distance is a key observable of gravitational-wave (GW) observations. We demonstrate how one can correctly retrieve the luminosity distance of compact binary coalescences (CBCs) if the GW signal is strongly lensed. We perform a proof-of-concept parameter estimation for the luminosity distance supposing (i) strong lensing produces two lensed GW signals emitted from a CBC, (ii) the Advanced LIGO-Virgo network detects both lensed signals as independent events, and (iii) the two events are identified as strongly lensed signals originated from the same source. Taking into account the maximum magnification allowed in two lensing scenarios and simulated GW signals emitted from four different binary black holes, we find that the strong lensing can improve the precision of the distance estimation of a CBC by up to a factor of a few compared to that can be expected without lensing.