LAUSR

Recent work has shown that modified gravitational wave (GW) propagation can be a powerful probe of dark energy and modified gravity, specific to GW observations. We use the technique of Gaussian processes, which allows the reconstruction of a function from the data without assuming any parametrization, to measurements of the GW luminosity distance from simulated joint GW-gamma-ray-burst detections, combined with measurements of the electromagnetic luminosity distance by simulated data from the dark energy survey (DES). For the GW events, we consider both a second-generation LIGO/Virgo/Kagra (HVLKI) network, and a third-generation detector such as the Einstein Telescope. We find that the HVLKI network at target sensitivity, with O(15) neutron star binaries with an electromagnetic counterpart, could already detect deviations from general relativity at a level predicted by some modified gravity models, and a third-generation detector such as the Einstein Telescope would have a remarkable discovery potential. We discuss the complementarity of the Gaussian processes technique to the (Ξ0,n) parametrization of modified GW propagation.