Distinguishing lensing and precessional modulation in binary black-hole inspiral waveforms
Abstract
Binary black holes (BBHs) emit gravitational waves (GWs) as they inspiral towards merger. These GWs can be gravitationally lensed by large-scale structure along the line of sight, potentially creating multiple images of the same source with fixed time delays determined by the lensing geometry. As the BBHs inspiral, the GW frequency increases, leading to successive constructive and destructive interference between the multiple images. BBHs also have spins Si that may be misaligned with their orbital angular momentum L. As the BBHs inspiral, these misaligned spins cause L to precess about the total angular momentum J, modulating the GW emission similar to pulsar emission resulting from a misaligned jet rotating in and out of the line of sight. We investigate the ability of a single L-shaped GW detector to distinguish between these two sources of modulation. We find that precessional modulation can mimic the lensing modulation between two images with comparable magnifications when the time delay between the images is short enough that fewer than three interference fringes occur during the time the GW signal spends in the sensitivity band of the detector. As strong lensing is rare for GW sources at moderate redshift while misaligned spins are common for BBHs produced in certain formation channels, ruling out precessional modulation is essential to identifying genuinely lensed systems.
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BibTeX
@misc{nguyenvo2026distinguishing,
title = {{Distinguishing lensing and precessional modulation in binary black-hole inspiral waveforms}},
author = {Tien N. Nguyen-Vo and Tamanjyot Singh and Benjamin McKallip and Michael Kesden and Lindsay King},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.06347},
eprint = {2609.06347},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.06347},
}
RIS
TY - UNPB
TI - Distinguishing lensing and precessional modulation in binary black-hole inspiral waveforms
AU - Tien N. Nguyen-Vo
AU - Tamanjyot Singh
AU - Benjamin McKallip
AU - Michael Kesden
AU - Lindsay King
PY - 2026
DA - 2026/09/06
PB - arXiv
DO - 10.48550/arxiv.2609.06347
UR - https://arxiv.org/abs/2609.06347
AB - Binary black holes (BBHs) emit gravitational waves (GWs) as they inspiral towards merger. These GWs can be gravitationally lensed by large-scale structure along the line of sight, potentially creating multiple images of the same source with fixed time delays determined by the lensing geometry. As the BBHs inspiral, the GW frequency increases, leading to successive constructive and destructive interference between the multiple images. BBHs also have spins S_i that may be misaligned with their orbital angular momentum L. As the BBHs inspiral, these misaligned spins cause L to precess about the total angular momentum J, modulating the GW emission similar to pulsar emission resulting from a misaligned jet rotating in and out of the line of sight. We investigate the ability of a single L-shaped GW detector to distinguish between these two sources of modulation. We find that precessional modulation can mimic the lensing modulation between two images with comparable magnifications when the time delay between the images is short enough that fewer than three interference fringes occur during the time the GW signal spends in the sensitivity band of the detector. As strong lensing is rare for GW sources at moderate redshift while misaligned spins are common for BBHs produced in certain formation channels, ruling out precessional modulation is essential to identifying genuinely lensed systems.
ER -