Reconnection-powered fast radio transients from coalescing neutron star binaries

TL;DR

This paper proposes that coalescing neutron star binaries with moderate magnetic fields can produce millisecond radio transients similar to fast radio bursts through magnetic reconnection in their magnetospheres.

Contribution

It introduces a novel mechanism where magnetic reconnection in neutron star binaries generates fast radio burst-like signals, supported by force-free electrodynamics simulations.

Findings

Millisecond radio transients can originate from neutron star mergers with sub-magnetar magnetic fields.

Reconnection-driven plasmoid formation leads to coherent electromagnetic emission.

Predicted frequencies of the bursts are in the 10-20 GHz range for typical magnetic field strengths.

Abstract

It is an open question whether and how gravitational wave events involving neutron stars can be preceded by electromagnetic counterparts. This work shows that the collision of two neutron stars with magnetic fields well below magnetar-level strengths can produce millisecond Fast-Radio-Burst-like transients. Using global force-free electrodynamics simulations, we demonstrate that electromagnetic flares, produced by overtwisted common flux tubes in the binary magnetosphere, collide with the orbital current sheet and compress it, resulting in enhanced magnetic reconnection. As a result, the current sheet fragments into a sequence of plasmoids, which collide with each other leading to the emission of coherent electromagnetic waves. The resulting millisecond-long burst of radiation should have frequencies in the range of $10-20\,\rm GHz$ for magnetic fields of $B^{\ast}=10^{11}\, \rm G$ at the stellar surfaces.