Search for Microlensing Signature in Gravitational Waves from Binary Black Hole Events

TL;DR

This paper reports a search for microlensing signatures in gravitational waves from binary black hole events using deep learning, finding no significant evidence but discussing the distinguishability of microlensed signals.

Contribution

It introduces a deep learning-based method for detecting microlensing in gravitational waves and applies it to real data, providing a new approach in this research area.

Findings

No significant microlensing evidence was found in the analyzed events.

One event was classified as potentially lensed but was statistically inconclusive.

The study discusses how microlensed signals can be distinguished from precessing black hole binaries.

Abstract

In a recent search (Kim et al. 2022), we looked for microlensing signature in gravitational waves from spectrograms of the binary black hole events in the first and second gravitational-wave transient catalogs. For the search, we have implemented a deep learning-based method (Kim et al. 2021) and figured out that one event, GW190707 093326, out of forty-six events, is classified into the lensed class. However, upon estimating the p-value of this event, we observed that the uncertainty of the p-value still includes the possibility of the event being unlensed. Therefore, we concluded that no significant evidence of beating patterns from the evaluated binary black hole events has found from the search. For a consequence study, we discuss the distinguishability between microlensed gravitational waves and the signal from precessing black hole binaries.