An assessment of the association between a fast radio burst and binary neutron star merger

Fast radio bursts (FRBs) are bright millisecond-duration radio bursts at cosmological distances. While young magnetars are the leading source candidate, recent observations suggest that there may be multiple FRB progenitor classes. Here we investigate a potential coincidence between a binary neutron star merger event, GW190425, and a bright, non-repeating FRB event, FRB 20190425A. The FRB is located within the gravitational wave sky localization area, occurred 2.5 h after the gravitational wave event and has a dispersion measure consistent with the distance inferred from gravitational wave parameter estimation. The chance probability of a coincidence between unrelated FRB and gravitational wave events in the searched databases is estimated to be 0.0052 (2.8σ). This potential association is consistent with the theory that the binary neutron star merger left behind a supramassive, highly magnetized compact object, which collapsed to form a black hole after losing angular momentum due to spindown and produced an FRB by ejecting the magnetosphere. If such a physical association is established, the equation of state of the post-merger compact object is likely to be stiff with a Tolman–Oppenheimer–Volkoff non-spinning maximum mass of >2.63−0.23+0.39solarmasses (>2.31−0.08+0.24solarmasses) for a neutron (quark) star remnant.