2022ApJ...930..139Z

Gravitational waves would attain birefringence during their propagation from distant sources to the Earth, when the charge, parity, and time reversal (CPT) symmetry is broken. If it was sizeable enough, such birefringence could be measured by the Advanced LIGO, Virgo, and KAGRA detector network. In this work, we place constraints on the birefringence of gravitational waves with the third observing run of this network, i.e., two catalogs GWTC-2 and GWTC-3. For the dispersion relation ω² = k² ± 2ζk³, our analysis shows the up-to-date strictest limit on the CPT-violating parameter, i.e., \zeta ={4.07}_{-5.79}^{+5.91}\times {10}^{-17}{\rm{m}}, at 68% confidence level. This limit is stricter by ∼5 times when compared to the existing one (∼2x 10^–16 m) and stands for the first ∼10 GeV-scale test of the CPT symmetry in gravitational waves. The results of the Bayes factor strongly disfavor the birefringence scenario of gravitational waves.