Tight bound on neutron-star radius with quasiperiodic oscillations in short gamma-ray bursts

TL;DR

This paper uses observed quasiperiodic oscillations in short gamma-ray bursts to infer neutron star properties, providing one of the tightest bounds on neutron star radius to date.

Contribution

It introduces a Bayesian method linking QPO frequencies to neutron star properties, improving radius estimates using postmerger oscillation data.

Findings

Estimated neutron star radius: 12.48 km for 1.4 solar masses.

Derived bounds on neutron star mass-radius relation.

Provided tight constraints on neutron star structure.

Abstract

Quasiperiodic oscillations (QPOs) have been recently discovered in the short gamma-ray bursts (GRBs) 910711 and 931101B. Their frequencies are consistent with those of the quasiradial and quadrupolar oscillations of binary neutron star merger remnants, as obtained in numerical relativity simulations. These simulations reveal quasiuniversal relations between the remnant oscillation frequencies and the tidal coupling constant of the binaries. Under the assumption that the observed QPOs are due to these postmerger oscillations, we use the frequency-tide relations in a Bayesian framework to infer the source redshift, as well as the chirp mass and the binary tidal deformability of the binary neutron star progenitors for GRBs 910711 and 931101B. We further use this inference to estimate bounds on the mass-radius relation for neutron stars. By combining the estimates from the two GRBs, we find a 68\% credible range $R_{1.4}=12.48^{+0.41}_{-0.40}$~km for the radius of a neutron star with mass $M=1.4$~M$_\odot$, which is one of the tightest bounds to date.