Prospects for neutrino observation and mass measurement from binary neutron star mergers
Phys. Rev. D 113, 123017 – Published 5 June, 2026
DOI: https://doi.org/10.1103/vlbb-gxr2
Abstract
Over the next decade, diffuse supernova neutrino background events are expected to be detected in the upcoming Hyper-Kamiokande experiment. Another neutrino source that has received far less attention in the context of neutrino detection is binary neutron star mergers. Including the data from multiple recent simulations, we find that detection in current and near-future neutrino experiments is not feasible, and a megaton-scale detector with threshold, such as the proposed Deep-TITAND, MEMPHYS, or MICA, will be required. This is primarily due to the updated binary neutron star merger rate and the time-of-flight delay caused by the nonzero neutrino mass. Regarding the former, recent results from the fourth observing run by LIGO, Virgo, and KAGRA has significantly lowered the upper limit on the neutron star merger rate. As for the latter, neutrino events from neutron star mergers are expected to be recorded shortly after the gravitational wave signal associated with the coalescence. Limiting the analysis to such short time windows can significantly reduce background rates. While this approach has been qualitatively discussed in the literature, the effect of the time delay caused by nonzero neutrino mass, which can substantially extend the observation windows, has been disregarded. We present a refined analysis employing energy-dependent time windows and luminosity distance cuts for the mergers and provide realistic estimates of the detector runtime required to record neutrinos from binary neutron star mergers with small background contamination. The relative timing between the neutrino and gravitational wave signals can also be employed to probe the scale of neutrino mass. We find that the sensitivity to the lightest neutrino mass exceeds both the most stringent terrestrial bounds from KATRIN and the projections based on galactic supernovae. This level of sensitivity may become particularly relevant in the future if terrestrial and supernova constraints are not significantly improved.
