Search for anisotropic, birefringent spacetime-symmetry breaking in gravitational wave propagation from GWTC-3
L. Haegel, Kellie O’Neal-Ault, Quentin G. Bailey, Jay D. Tasson, Malachy Bloom, Lijing Shao
Abstract
An effective-field theory framework, the Standard Model Extension, is used to investigate the existence of Lorentz and $CPT$-violating effects during gravitational wave propagation. We implement a modified equation for the dispersion of gravitational waves that includes isotropic, anisotropic and birefringent dispersion. Using the LIGO-Virgo-KAGRA algorithm library suite, we perform a joint Bayesian inference of the source parameters and coefficients for spacetime-symmetry breaking. From a sample of 45 high-confidence events selected in the GWTC-3 catalog, we obtain a maximal bound of $3.19\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}15}\text{ }\text{ }\mathrm{m}$ at 90% CI for the isotropic coefficient ${k}_{(V)00}^{(5)}$ when assuming the anisotropic coefficients to be zero. The combined measurement of all the dispersion parameters yields limits on the order of ${10}^{\ensuremath{-}13}\text{ }\text{ }\mathrm{m}$ for the 16 ${k}_{(V)ij}^{(5)}$ coefficients. We study the robustness of our inference by comparing the constraints obtained with different waveform models, and find that a lack of physics in the simulated waveform may appear as spacetime-symmetry breaking-induced dispersion for a subset of events.