Event rate predictions of strongly lensed gravitational waves with detector networks and more realistic templates

TL;DR

This paper predicts the detection rates of strongly lensed gravitational waves using realistic templates and detector networks, finding significant improvements especially for third-generation detectors, and estimates hundreds of such events per year.

Contribution

It introduces a comprehensive simulation incorporating Earth's rotation and realistic wave templates to improve lensed GW event rate predictions across multiple detector generations.

Findings

Detection rate increases by ~37% with realistic templates.

Network detection further boosts rates by ~58%.

Third-generation detectors could observe hundreds of lensed events annually.

Abstract

Strong lensing of gravitational waves (GWs) is attracting growing attention of the community. The event rates of lensed GWs by galaxies were predicted in numerous papers, which used some approximations to evaluate the GW strains detectable by a single detector. The joint-detection of GW signals by a network of instruments will increase the detecting ability of fainter and farther GW signals, which could increase the detection rate of the lensed GWs, especially for the 3rd generation detectors, e.g., Einstein Telescope (ET) and Cosmic Explorer (CE). Moreover, realistic GW templates will improve the accuracy of the prediction. In this work, we consider the detection of galaxy-scale lensed GW events under the 2nd, 2.5th, and 3rd generation detectors with the network scenarios and adopt the realistic templates to simulate GW signals. Our forecast is based on the Monte Carlo technique which enables us to take Earth's rotation into consideration. We find that the overall detection rate is improved, especially for the 3rd generation detector scenarios. More precisely, it increases by ~37% adopting realistic templates, and under network detection strategy, further increases by ~58% comparing with adoption of the realistic templates, and we estimate that the 3rd generation GW detectors will detect hundreds lensed events per year. The effect from the Earth's rotation is weakened in the detector network strategy.