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Line-of-sight acceleration in compact binaries with higher harmonics and eccentricity

Soumen Roy* and Justin Janquart

  • *Contact author: soumen.roy@uclouvain.be
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Phys. Rev. D 114, 044075 – Published 24 August, 2026

DOI: https://doi.org/10.1103/3r53-k7hq

Abstract

Direct detections of gravitational waves provide a unique opportunity to probe the astrophysical origin of compact binary mergers. The formation channels of these systems remain highly debated, and a fraction may originate in dynamical environments or active galactic nuclei. Binaries formed in such environments are expected to experience line-of-sight acceleration from their surroundings, which can imprint characteristic signatures on the observed gravitational wave signal. Here, we rederive the line-of-sight acceleration effects and implement them in state-of-the-art quasicircular waveform models with precession and higher-order modes. We also implement the corrections in eccentric waveform models, applying them consistently to all contributing harmonics. Using this model, we investigate the impact of these effects on the inference of line-of-sight acceleration and analyze several selected events from the Gravitational-Wave Transient Catalog observed during the third observing run of LIGO and Virgo. We find no substantial evidence for line-of-sight acceleration in these events. We also show that an inconsistent treatment of line-of-sight acceleration between higher harmonics can lead to biased conclusions. Our model provides a robust framework for uncovering line-of-sight acceleration in current and future gravitational wave observations, enabling more accurate probes of environmental signatures in compact binary formation.

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Phys. Rev. D 114, 044075– Published 24 August, 2026
  • Received 10 June 2026
  • Accepted 31 July 2026
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