Joint Gravitational-Wave and High-Energy Neutrino Detections From Binary Neutron Star Mergers: A Rate Estimate

Binary neutron star mergers are the one source class guaranteed to emit gravitational waves and plausibly able to emit high-energy neutrinos from a relativistic jet. This paper computes how often both messengers should be detected together. With a merger rate density of 300 per cubic gigaparsec per year and a gravitational-wave horizon of 200 Mpc enclosing 0.0335 cubic gigaparsecs, about 10.1 mergers per year are gravitationally detectable. Requiring a jet pointed at Earth, with beaming fraction 0.02, and neutrino detectability to 40 Mpc reduces the joint on-axis rate to 0.00161 per year — one joint event per 622 years. An isotropic cocoon component detectable to 15 Mpc fares little better: 0.00424 per year, one per 236 years. Joint gravitational-wave and high-energy neutrino astronomy of mergers is, on these numbers, a programme for much larger neutrino detectors or much nearer luck, not for current instruments. The negative result is stated plainly. The study is computed from stated assumptions, not measured.