The LIGO-Virgo-KAGRA Collaboration recently reported an exceptional gravitational-wave event, GW231123. This gravitational-wave signal was assumed to be generated from the merger of a binary black hole system, with source frame masses of 137−17+22M⊙ and 103−52+20M⊙ (90\% credible intervals). As seen by the two LIGO detectors, the signal has only ∼5 cycles, between 30 and 80 Hz, over ∼10 ms. It is of critical importance to confirm the origin of this signal. Here we present the results of a Bayesian model comparison to test whether the gravitational-wave signal was actually generated by a binary black hole merger, or emitted from cusps or kinks on a cosmic string. We find significant evidence for a binary black hole merger origin of the signal.
@article{arxiv.2507.20778,
title = {GW231123: Binary Black Hole Merger or Cosmic String?},
author = {Iuliu Cuceu and Marie Anne Bizouard and Nelson Christensen and Mairi Sakellariadou},
journal= {arXiv preprint arXiv:2507.20778},
year = {2026}
}