Testing mirror symmetry in the Universe with LIGO-Virgo black-hole mergers Articles uri icon

authors

publication date

  • January 2025

start page

  • 031402-1

end page

  • 031402-10

issue

  • 3

volume

  • 134

International Standard Serial Number (ISSN)

  • 0031-9007

Electronic International Standard Serial Number (EISSN)

  • 1079-7114

abstract

  • Certain precessing black-hole mergers produce gravitational waves with net circular polarization, understood as an imbalance between right- and left-handed amplitudes. According to the cosmological principle, such emission must average to zero across all binary mergers in our Universe to preserve mirror-reflection symmetry at very large scales. We present a new independent gravitational-wave test of this hypothesis. Using a novel observable based on the Chern-Pontryagin pseudoscalar, we measure the emission of net circular polarization across 47 black-hole mergers recently analyzed by [T. Islam et al., arXiv:2309.14473.] with a state-of-the art model for precessing black-hole mergers in general relativity. The average value obtained is consistent with zero. Remarkably, however, we find that at least 82% of the analyzed sources must have produced net circular polarization. Of these, GW200129 shows strong evidence for mirror asymmetry, with a Bayes factor of 12.6 or, equivalently, 93.1% probability. We obtain consistent (although stronger) results of 97.5% and 94.3%, respectively, using public results on this event from [M. Hannam et al., Nature (London) 610, 652 (2022).] and performing our own parameter inference. This finding further implies evidence of astrophysical sources that can spontaneously emit circularly polarized photons by quantum effects. Forthcoming black-hole merger detections will enable stronger constraints on large-scale mirror asymmetry and the cosmological principle.

subjects

  • Mathematics