Classifying Lensed Gravitational Waves in the Geometrical Optics Limit with Machine Learning

TL;DR

This paper demonstrates that machine learning classifiers can effectively distinguish gravitational wave signals that are gravitationally lensed, potentially improving detection and analysis of such events in future gravitational wave observations.

Contribution

The study applies supervised machine learning models to classify lensed versus unlensed gravitational waves using spectrogram data, showing high accuracy and suggesting a new approach for detection.

Findings

Support vector machine achieved F1 score of 0.996

Random forest achieved F1 score of 0.952

Classifiers effectively discriminate lensed signals in simulated data

Abstract

Gravitational waves are theorized to be gravitationally lensed when they propagate near massive objects. Such lensing effects cause potentially detectable repeated gravitational wave patterns in ground- and space-based gravitational wave detectors. These effects are difficult to discriminate when the lens is small and the repeated patterns superpose. Traditionally, matched filtering techniques are used to identify gravitational-wave signals, but we instead aim to utilize machine learning techniques to achieve this. In this work, we implement supervised machine learning classifiers (support vector machine, random forest, multi-layer perceptron) to discriminate such lensing patterns in gravitational wave data. We train classifiers with spectrograms of both lensed and unlensed waves using both point-mass and singular isothermal sphere lens models. As the result, classifiers return F1 scores ranging from 0.852 to 0.996, with precisions from 0.917 to 0.992 and recalls ranging from 0.796 to 1.000 depending on the type of classifier and lensing model used. This supports the idea that machine learning classifiers are able to correctly determine lensed gravitational wave signals. This also suggests that in the future, machine learning classifiers may be used as a possible alternative to identify lensed gravitational wave events and to allow us to study gravitational wave sources and massive astronomical objects through further analysis.