Kilohertz quasiperiodic oscillations in short gamma-ray bursts

TL;DR

This paper reports the detection of kilohertz quasiperiodic oscillations in short gamma-ray bursts, suggesting a link to neutron star mergers and post-merger dynamics, with potential implications for future gravitational wave observations.

Contribution

It presents the first identification of kilohertz quasiperiodic signals in short gamma-ray bursts, aligning observational data with numerical relativity predictions.

Findings

Detected quasiperiodic signals in GRB 910711 and GRB 931101B

Signals are compatible with post-merger neutron star oscillations

Supports the connection between gamma-ray bursts and neutron star mergers

Abstract

Short gamma-ray bursts are associated with binary neutron star mergers, which are multimessenger astronomical events that have been observed both in gravitational waves and in the multiband electromagnetic spectrum. Depending on the masses of the stars in the binary and on details of their largely unknown equation of state, a dynamically evolving and short-lived neutron star may be formed after the merger, existing for approximately 10-300 ms before collapsing to a black hole. Numerical relativity simulations across different groups consistently show broad power spectral features in the 1-5 kHz range in the post-merger gravitational wave signal, which is inaccessible by current gravitational-wave detectors but could be seen by future third generation ground-based detectors in the next decade. This implies the possibility of quasiperiodic modulation of the emitted gamma-rays in a subset of events where a neutron star is formed shortly prior to the final collapse to a black hole. Here we present two such signals identified in the short bursts GRB 910711 and GRB 931101B from archival BATSE data, which are compatible with the predictions from numerical relativity.