Cosmology with Gravitational Wave/Fast Radio Burst Associations

Recently, some theoretical models predicted that a small fraction of fast radio bursts (FRBs) could be associated with gravitational waves (GWs). In this Letter, we discuss the possibility of using GW/FRB association systems, if they are commonly detected in the future, as a complementary cosmic probe. We propose that upgraded standard sirens can be constructed from the joint measurements of luminosity distances DL derived from GWs and dispersion measures DMIGM derived from FRBs (i.e., the combination DL DMIGM). Moreover, unlike the traditional standard-siren approach (i.e., the DL method) and the DMIGM method that rely on the optimization of the Hubble constant H0, this DL DMIGM method has the advantage of being independent of H0. Through Monte Carlo simulations, we prove that the DL DMIGM method is more effective for constraining cosmological parameters than DL or DMIGM separately, and that it enables us to achieve accurate multimessenger cosmology from approximately 100 GW/FRB systems. Additionally, even if GW/FRB associations do not exist, the methodology developed here can still be applied to those GWs and FRBs that occur at the same redshifts.