Measuring the Hubble constant with a sample of kilonovae

Kilonovae produced by the coalescence of compact binaries with at least one neutron star are promising standard sirens for an independent measurement of the Hubble constant (H0). Through their detection via follow-up of gravitational-wave (GW), short gamma-ray bursts (sGRBs) or optical surveys, a large sample of kilonovae (even without GW data) can be used for H0 contraints. Here, we show measurement of H0 using light curves associated with four sGRBs, assuming these are attributable to kilonovae, combined with GW170817. Including a systematic uncertainty on the models that is as large as the statistical ones, we find $${H}_{0}=73.{8}_{-5.8}^{+6.3}\ {\rm{km}}\ {{\rm{s}}}^{-1}\ {{\rm{Mpc}}}^{-1}$$ H 0 = 73 . 8 − 5.8 + 6.3 km s − 1 Mpc − 1 and $${H}_{0}=71.{2}_{-3.1}^{+3.2}\ {\rm{km}}\ {{\rm{s}}}^{-1}\ {{\rm{Mpc}}}^{-1}$$ H 0 = 71 . 2 − 3.1 + 3.2 km s − 1 Mpc − 1 for two different kilonova models that are consistent with the local and inverse-distance ladder measurements. For a given model, this measurement is about a factor of 2-3 more precise than the standard-siren measurement for GW170817 using only GWs.