Resonant Shattering of Neutron Star Crusts

TL;DR

This paper explores how tidal resonances in neutron stars can cause crust shattering, producing observable gamma-ray burst precursors and providing insights into neutron star structure and the crust-core boundary.

Contribution

It demonstrates that resonant excitation of neutron star modes can lead to crust shattering, linking precursor observations to neutron star equation of state constraints.

Findings

Crust shattering releases ~10^46-10^47 erg energy.

Precursor timing constrains crust equation of state.

Observations can complement gravitational wave data.

Abstract

The resonant excitation of neutron star (NS) modes by tides is investigated as a source of short gamma-ray burst (sGRB) precursors. We find that the driving of a crust-core interface mode can lead to shattering of the NS crust, liberating ~10^46-10^47 erg of energy seconds before the merger of a NS-NS or NS-black hole binary. Such properties are consistent with Swift/BAT detections of sGRB precursors, and we use the timing of the observed precursors to place weak constraints on the crust equation of state. We describe how a larger sample of precursor detections could be used alongside coincident gravitational wave detections of the inspiral by Advanced LIGO class detectors to probe the NS structure. These two types of observations nicely complement one another, since the former constrains the equation of state and structure near the crust-core boundary, while the latter is more sensitive to the core equation of state.