Identifying strongly lensed gravitational waves through their phase consistency

Abstract

Strongly lensed gravitational waves (GWs) from binary coalescence manifest as repeated chirps from the original merger. At the detectors, the phase of the lensed GWs and its arrival time differences will be consistent modulo a fixed constant phase shift. We develop a fast and reliable method to efficiently reject event pairs that are not-lensed copies and appropriately rank the most interesting candidates. Our method exploits that detector phases are the best measured GW parameter, with errors only of a fraction of a radian and differences across the frequency band that are better measured than the chirp mass. The arrival time phase differences also avoid the shortcomings of looking for overlaps in highly non-Gaussian sky maps. Our basic statistic determining the consistency with lensing is the distance between the phase posteriors of two events and it directly provides information about the lens-source geometry which helps inform electromagnetic followups. We demonstrate that for simulated signals of not-lensed binaries specifically chosen with many coincident properties so as to trigger false lensing alarms none of the pairs have phases closer than $3\sigma$, and most cases reject the lensing hypothesis by $5\sigma$. Looking at the latest catalog, GWTC3, we find that only $6\%$ of the pairs are consistent with lensing at 99\% confidence level. Moreover, we reject about half of the pairs that would otherwise favor lensing by their parameter overlaps and demonstrate good correlation with detailed joint parameter estimation results. This reduction of the false alarm rate will be of paramount importance in the upcoming observing runs and the eventual discovery of lensed GWs. Our code is publicly available and could be applied beyond lensing to test possible deviations in the phase evolution from modified theories of gravity and constrain GW birefringence.

arXiv comment14+7 pages, 12+7 figures, 2 tables, code at https://github.com/ezquiaga/phazap. Matches PRD version

References in corpus (32)

• Observation of Gravitational Waves from a Binary Black Hole Merger
• Advanced Virgo: a 2nd generation interferometric gravitational wave detector
• Advanced LIGO
• Gravitational Waves from Mergin Compact Binaries: How Accurately Can One Extract the Binary's Parameters from the Inspiral Waveform?
• Bilby: A user-friendly Bayesian inference library for gravitational-wave astronomy
• Observing binary inspiral in gravitational radiation: One interferometer
• Computationally efficient models for the dominant and sub-dominant harmonic modes of precessing binary black holes
• Networks of gravitational wave detectors and three figures of merit
• IMRPhenomXHM: A multi-mode frequency-domain model for the gravitational wave signal from non-precessing black-hole binaries
• An excess power statistic for detection of burst sources of gravitational radiation
• Concordance and Discordance in Cosmology
• Search for gravitational lensing signatures in LIGO-Virgo binary black hole events
• Precise LIGO Lensing Rate Predictions for Binary Black Holes
• Characterization of systematic error in Advanced LIGO calibration
• Calibration Uncertainty for Advanced LIGO's First and Second Observing Runs
• Phase effects from strong gravitational lensing of gravitational waves
• Localizing merging black holes with sub-arcsecond precision using gravitational-wave lensing
• Please repeat: Strong lensing of gravitational waves as a probe of compact binary and galaxy populations
• Identifying strong gravitational-wave lensing during the second observing run of Advanced LIGO and Advanced Virgo
• Identifying Type II Strongly Lensed Gravitational-Wave Images in Third-Generation Gravitational-Wave Detectors
• A fast and precise methodology to search for and analyse strongly lensed gravitational-wave events
• Non-Gaussian estimates of tensions in cosmological parameters
• Bayesian statistical framework for identifying strongly lensed gravitational-wave signals
• Follow-up Analyses to the O3 LIGO-Virgo-KAGRA Lensing Searches
• On the identification of individual gravitational wave image types of a lensed system using higher-order modes
• Discovering gravitationally lensed gravitational waves: predicted rates, candidate selection, and localization with the Vera Rubin Observatory
• Rapid Identification of Strongly Lensed Gravitational-Wave Events with Machine Learning
• Removing degeneracy and multimodality in gravitational wave source parameters
• Lensing or luck? False alarm probabilities for gravitational lensing of gravitational waves
• Detection and parameter estimation challenges of Type-II lensed binary black hole signals
• Parametrizing gravitational-wave polarizations
• The Return of GOLUM: Improving Distributed Joint Parameter Estimation for Strongly-Lensed Gravitational Waves

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• TESLA-X: An effective method to search for sub-threshold lensed gravitational waves with a targeted population model
• Phase consistency test to identify type II strongly lensed gravitational wave signals using a single event
• A ${\chi }^2$ statistic for the identification of strongly lensed gravitational waves from compact binary coalescences
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