kHz quasi-periodic oscillations in BATSE GRBs 910711 and 931101B

Short gamma ray bursts (GRBs) have already been associated with binary neutron star mergers, which are also sources of gravitational waves. Numerical relativity simulations indicate that the merger can form a short-lived hypermassive neutron star (i.e. a millisecond magnetar), lasting for tens to hundreds of milliseconds before gravitational collapse forms a black hole. This neutron star remnant is expected to emit gravitational waves with kHz frequencies that will be detectable by third generation ground-based GW detectors in the 2030s. We will report on the discovery of kHz quasiperiodic oscillations in GRBs 910711 and 931101B, providing evidence for a hypermassive neutron star stage in these events.