A $χ^2$ statistic for the identification of strongly lensed gravitational waves from compact binary coalescences

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Autori principali: Gholap, Sudhir, Soni, Kanchan, Kapadia, Shasvath J., Dhurandhar, Sanjeev
Natura: Preprint
Pubblicazione: 2025
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author Gholap, Sudhir
Soni, Kanchan
Kapadia, Shasvath J.
Dhurandhar, Sanjeev
author_facet Gholap, Sudhir
Soni, Kanchan
Kapadia, Shasvath J.
Dhurandhar, Sanjeev
contents Gravitational waves (GWs) emanated by stellar mass compact binary coalescences (CBCs), and lensed by galaxy- or cluster-scale lenses, will produce two or more copies of the GW signal. These will have identical phase evolution but differing amplitudes. Such lensing signatures are expected to be detected by the end of the LIGO-Virgo-Kagra's (LVK's) fifth observing run (O5). In this work, we propose a novel $χ_{\mathrm{lens}}^2$ statistic to segregate pairs of detected GW events as either lensed or unlensed, using templates typically used in GW searches. The statistic is an application of the generalized $χ^2$ discriminator described in \citet{dhurandhar2017}, tailored to probe the similarity (or lack thereof) between the phase evolutions of two CBC signals. We assess the performance of $χ_{\mathrm{lens}}^2$ on a realistic astrophysical dataset of lensed and unlensed CBCs detectable in O4, assuming a single LIGO-like detector at design sensitivity. We find that we can correctly identify lensed events with efficiencies comparable to existing Bayesian and machine learning methods. Evaluating $χ_{\mathrm{lens}}^2$ is orders of magnitude faster than Bayesian methods. Moreover, the statistics of $χ_{\mathrm{lens}}^2$, in stationary Gaussian noise, are fully understood, in contrast to machine learning methods. $χ_{\mathrm{lens}}^2$ can, therefore, be used to rapidly and accurately weed out the vast majority of unlensed candidate pairs and identify lensed pairs.
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id arxiv_https___arxiv_org_abs_2502_00844
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A $χ^2$ statistic for the identification of strongly lensed gravitational waves from compact binary coalescences
Gholap, Sudhir
Soni, Kanchan
Kapadia, Shasvath J.
Dhurandhar, Sanjeev
General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
Instrumentation and Methods for Astrophysics
Gravitational waves (GWs) emanated by stellar mass compact binary coalescences (CBCs), and lensed by galaxy- or cluster-scale lenses, will produce two or more copies of the GW signal. These will have identical phase evolution but differing amplitudes. Such lensing signatures are expected to be detected by the end of the LIGO-Virgo-Kagra's (LVK's) fifth observing run (O5). In this work, we propose a novel $χ_{\mathrm{lens}}^2$ statistic to segregate pairs of detected GW events as either lensed or unlensed, using templates typically used in GW searches. The statistic is an application of the generalized $χ^2$ discriminator described in \citet{dhurandhar2017}, tailored to probe the similarity (or lack thereof) between the phase evolutions of two CBC signals. We assess the performance of $χ_{\mathrm{lens}}^2$ on a realistic astrophysical dataset of lensed and unlensed CBCs detectable in O4, assuming a single LIGO-like detector at design sensitivity. We find that we can correctly identify lensed events with efficiencies comparable to existing Bayesian and machine learning methods. Evaluating $χ_{\mathrm{lens}}^2$ is orders of magnitude faster than Bayesian methods. Moreover, the statistics of $χ_{\mathrm{lens}}^2$, in stationary Gaussian noise, are fully understood, in contrast to machine learning methods. $χ_{\mathrm{lens}}^2$ can, therefore, be used to rapidly and accurately weed out the vast majority of unlensed candidate pairs and identify lensed pairs.
title A $χ^2$ statistic for the identification of strongly lensed gravitational waves from compact binary coalescences
topic General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2502.00844