2025ApJ...985L..45Y

The origin of repeating fast radio bursts (rFRBs) is an open question, with observations suggesting that at least some are associated with old stellar populations. It has been proposed that some rFRBs may be produced by interactions of the binary neutron star (BNS) magnetospheres decades to centuries before the coalescence. These systems would also emit centi-Hertz gravitational waves during this period, which can be detectable by spaceborne gravitational wave detectors. We explore the prospects of using current and future spaceborne gravitational wave detectors, such as TianQin, LISA, and DECIGO, to test this fast radio burst (FRB) formation hypothesis. Focusing on nearby galaxies like M81, which hosts an rFRB source in a globular cluster, we calculate the detection capabilities for BNS systems. Our analysis reveals that while missions like TianQin and LISA face limitations in horizon distance, changing the detector pointing direction could significantly enhance detection probabilities. Considering that the chance of a Milky Way-like galaxy coincidentally containing a BNS within 100 yr before merger is only 3 × 10^–5-5 × 10^–3, if a signal is detected originating from M81, we can establish the link between FRBs and BNSs with a significance level of at least 2.81σ. For TianQin and LISA, Bayes factors for rFRB-BNS associations range from 4 × 10⁶ to 7 × 10⁸ under ideal assumptions of uniform event distribution, dropping to 5 × 10²-10⁵ when accounting for the fact that the events are confined in galaxies. Next-generation detectors such as DECIGO offer enhanced capabilities compared to TianQin and LISA and should easily detect these systems in M81 and beyond. DECIGO can boost the Bayes factor by up to 4 orders of magnitude (10¹⁰-10¹² ideally and 10⁴-10⁶ realistically). Our work highlights the critical role of spaceborne gravitational wave missions in unraveling FRB origins.