| Astrophysics (Index) | About |
A neutron-star black-hole merger (NSBH merger, aka black-hole neutron-star merger, BHNS merger), the joining of a neutron star and a black hole occurs when the orbit of a neutron-star black-hole binary becomes sufficiently small that gravitational waves sap energy from the orbit producing a runaway orbital decay. When the two merge, a gravitational wave event may result, and the ground gravitational-wave detectors, LIGO and Virgo can detect them within a certain distance. Black hole mergers are detected far more often: for example, among the 60+ GW detections of LIGO Observing Runs, O1-O3, only three have been identified as NSBH mergers (and only three neutron star mergers).
(A factor that contributes to this trend is that mergers of more massive objects, i.e., black holes, produce waves detectable over a longer distance.)