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 work, we discuss the possibility of using GW/FRB association systems, if 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 $D_L$ derived from GWs and dispersion measures ${\rm DM_{IGM}}$derivedfromFRBs(i\mathrm{.}e\mathrm{.},thecombination$D_{L}\cdot{\rm DM_{IGM}}$). Moreover, unlike the traditional standard-siren approach (i.e., the $D_L$ method) and the $\mathrm{D}{\mathrm{M}}_{\mathrm{I}\mathrm{G}\mathrm{M}}$ method that rely on the optimization of the Hubble constant $H_0$, this $D_L\cdot \mathrm{D}{\mathrm{M}}_{\mathrm{I}\mathrm{G}\mathrm{M}}$ method has the advantage of being independent of $H_0$. Through Monte Carlo simulations, we prove that the $D_L\cdot \mathrm{D}{\mathrm{M}}_{\mathrm{I}\mathrm{G}\mathrm{M}}$ method is more effective to constrain cosmological parameters than $D_L$ or $\mathrm{D}{\mathrm{M}}_{\mathrm{I}\mathrm{G}\mathrm{M}}$ separately, and enables us to achieve accurate multimessenger cosmology from around 100 GW/FRB systems. Additionally, even if GW/FRB associations are not exist, the methodology developed here can still be applied to those GWs and FRBs that occur at the same redshifts.