2024RAA....24h5004R

Theories of modified gravity suggest that the propagation speed of gravitational waves (GW) v_g may deviate from the speed of light c. A constraint can be placed on the difference between c and v_g with a simple method that uses the arrival time delay between GW and electromagnetic wave simultaneously emitted from a burst event. We simulated the joint observation of GW and short gamma-ray burst signals from binary neutron star merger events in different observation campaigns, involving advanced LIGO (aLIGO) in design sensitivity and Einstein Telescope (ET) joint-detected with Fermi/GBM. As a result, the relative precision of constraint on v_g can reach ∼10^–17 (aLIGO) and ∼10^–18 (ET), which are one and two orders of magnitude better than that from GW170817, respectively. We continue to obtain the bound of graviton mass m_g ≤ 7.1(3.2) × 10^–20 eV with aLIGO (ET). Applying the Standard-Model Extension test framework, the constraint on v_g allows us to study the Lorentz violation in the nondispersive, nonbirefringent limit of the gravitational sector. We obtain the constraints of the dimensionless isotropic coefficients ${\bar{s}}_{00}^{(4)}$ at mass dimension d = 4, which are $-1\times {10}^{-15}\lt {\bar{s}}_{00}^{(4)}\lt 9\,\times \,{10}^{-17}$ for aLIGO and $-4\times {10}^{-16}\lt {\bar{s}}_{00}^{(4)}\lt 8\,\times \,{10}^{-18}$ for ET.