Tests of GravitationalWave Birefringence with the Open GravitationalWave Catalog
Abstract
The routine detection of gravitationalwave events from compact binary coalescences has allowed precise tests of gravity in strong field, dynamical field, and high energy regime. In this work, we report the results of testing gravitationalwave birefringence using compact binary coalescence events from the 3rd Open Gravitationalwave Catalog (3OGC). Birefringence, an effect where the left and righthanded polarizations of gravitational waves follow different equations of motion, occurs when the parity symmetry of gravity is broken. This arises naturally in the effective field theory extension of general relativity. Using Bayesian inference and stateoftheart waveform modeling, we use all events in 3OGC to constrain the lower limit of the energy scale at which parity violation effects emerge. Overall we do not find evidence for a violation of general relativity, and thus we constrain the parityviolating energy scale to $M_\mathrm{PV} > 0.11$ GeV at $90\%$ confidence level, which is an improvement over previous results by one order of magnitude. Intriguingly, we find an outlier, GW190521, that supports the existence of birefringence over general relativity with a higher matchfiltering signaltonoise ratio and Bayes factor. The inclusion of birefringence for GW190521 gives consistent sky location estimation with a possible electromagnetic counterpart reported Zwicky Transient Facility (ZTF).However, the inferred $M_\mathrm{PV}$ from GW190521 is in tension with the combined constraints from other events, we thus hypothesize that the nonzero deviation may be caused by the limitations of the existing waveform approximants. More gravitational wave detections in the future from compact binary coalescence will further improve the constraints on birefringence and shed light on possible systematics for GW190521type events.
 Publication:

arXiv eprints
 Pub Date:
 September 2021
 arXiv:
 arXiv:2109.09718
 Bibcode:
 2021arXiv210909718W
 Keywords:

 Astrophysics  High Energy Astrophysical Phenomena;
 General Relativity and Quantum Cosmology
 EPrint:
 v2: fix eq.4 that assumed small phase expansion, rerun GW190521. Data and codes in https://github.com/gwastro/3ogc_birefringence