The missing link: Merging neutron stars naturally produce jet-like structures and can power short Gamma-Ray Bursts

TL;DR

This study demonstrates through simulations that merging magnetized neutron stars can produce jet-like structures and conditions suitable for powering short Gamma-Ray Bursts, aligning with observational data.

Contribution

It provides the first ab-initio simulation showing how neutron star mergers naturally generate jets capable of explaining SGRB central engines.

Findings

Merger results in a rapidly spinning black hole with a magnetized torus.

Magnetic fields are amplified from ~10^{12} G to ~10^{15} G.

Simulations align with observed properties of short Gamma-Ray Bursts.

Abstract

Short Gamma-Ray Bursts (SGRBs) are among the most luminous explosions in the universe, releasing in less than one second the energy emitted by our Galaxy over one year. Despite decades of observations, the nature of their "central-engine" remains unknown. Considering a binary of magnetized neutron stars and solving Einstein equations, we show that their merger results in a rapidly spinning black hole surrounded by a hot and highly magnetized torus. Lasting over 35 ms and much longer than previous simulations, our study reveals that magnetohydrodynamical instabilities amplify an initially turbulent magnetic field of ~ 10^{12} G to produce an ordered poloidal field of ~ 10^{15} G along the black-hole spin-axis, within a half-opening angle of ~ 30 deg, which may naturally launch a relativistic jet. The broad consistency of our ab-initio calculations with SGRB observations shows that the merger of magnetized neutron stars can provide the basic physical conditions for the central-engine of SGRBs.