Across the Universe: GW231123 as a Magnified and Diffracted Black Hole Merger
- 1Max Planck Institute for Gravitational Physics (Albert Einstein Institute) Am Mühlenberg 1
Abstract
GW231123 is the most massive binary black hole merger observed to date by the LIGO–Virgo–KAGRA detectors, with a reported total mass of 190–265 M ⊙ (90% confidence level, c.l.). Such a high observed mass can result from the combined effects of cosmological redshift and gravitational magnification if the source is gravitationally lensed. In addition, compact objects such as stellar remnants can induce wave-optics diffraction, imprinting characteristic distortions on the signal. We present a multiscale lensing analysis of GW231123 that incorporates diffraction by a compact microlens embedded in an external gravitational potential. The data favor a lensed interpretation with a conservative false-alarm probability of ≲1%. The inferred total source mass shifts to 100–180 M ⊙ , reducing the need for extreme spins and tensions between waveform models. We reconstruct both source and lens parameters, including the microlens mass (190–850 M ⊙ ), its projected offset, and the amplitude and orientation of the external potential. Assuming a galaxy-scale macrolens modeled as a singular isothermal sphere, we infer external magnification that places the source at redshift z ∼ 0.7–2 and predicts a ∼55% probability of forming an additional detectable image. This analysis demonstrates how current gravitational-wave observations probe the wave-optics lensing regime, enabling joint inference of compact lenses and macroscopic gravitational potentials, including bounds on compact dark matter. Continued searches for additional macroimages and diffraction by stellar fields will further test GW231123 as a lensed event candidate.
Related
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BibTeX
@article{goyal2026across,
title = {{Across the Universe: GW231123 as a Magnified and Diffracted Black Hole Merger}},
author = {Srashti Goyal and Hector Villarrubia-Rojo and Miguel Zumalacárregui},
journal = {The Astrophysical Journal Letters},
year = {2026},
month = aug,
doi = {10.3847/2041-8213/ae93b1},
url = {https://doi.org/10.3847/2041-8213/ae93b1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Across the Universe: GW231123 as a Magnified and Diffracted Black Hole Merger
AU - Srashti Goyal
AU - Hector Villarrubia-Rojo
AU - Miguel Zumalacárregui
PY - 2026
DA - 2026/08/25
JO - The Astrophysical Journal Letters
DO - 10.3847/2041-8213/ae93b1
UR - https://doi.org/10.3847/2041-8213/ae93b1
AB - GW231123 is the most massive binary black hole merger observed to date by the LIGO–Virgo–KAGRA detectors, with a reported total mass of 190–265 M ⊙ (90% confidence level, c.l.). Such a high observed mass can result from the combined effects of cosmological redshift and gravitational magnification if the source is gravitationally lensed. In addition, compact objects such as stellar remnants can induce wave-optics diffraction, imprinting characteristic distortions on the signal. We present a multiscale lensing analysis of GW231123 that incorporates diffraction by a compact microlens embedded in an external gravitational potential. The data favor a lensed interpretation with a conservative false-alarm probability of ≲1%. The inferred total source mass shifts to 100–180 M ⊙ , reducing the need for extreme spins and tensions between waveform models. We reconstruct both source and lens parameters, including the microlens mass (190–850 M ⊙ ), its projected offset, and the amplitude and orientation of the external potential. Assuming a galaxy-scale macrolens modeled as a singular isothermal sphere, we infer external magnification that places the source at redshift z ∼ 0.7–2 and predicts a ∼55% probability of forming an additional detectable image. This analysis demonstrates how current gravitational-wave observations probe the wave-optics lensing regime, enabling joint inference of compact lenses and macroscopic gravitational potentials, including bounds on compact dark matter. Continued searches for additional macroimages and diffraction by stellar fields will further test GW231123 as a lensed event candidate.
SN - 2041-8205
SN - 2041-8213
ER -