Production of Jets before Neutron Star Mergers

TL;DR

This paper models how magnetospheric interactions between merging neutron stars produce dual jets, potentially observable as precursor emissions before gravitational wave signals, using advanced 3D relativistic MHD simulations.

Contribution

It introduces a novel simulation of neutron star mergers showing dual-jetted outflows driven by magnetospheric interactions, analogous to planetary Alfvén wings.

Findings

Generation of dual jets enhances precursor electromagnetic signals.

Magnetic field amplification occurs near the stellar surface.

Observable modulations in emission are predicted before mergers.

Abstract

We demonstrate that magnetospheric interactions between merging neutron stars (NSs) generate dual-jetted current outflows, analogous to the Alfv\'{e}n wings observed during planetary interactions in the Solar System. Using 3D relativistic MHD simulations, we model the interaction as a conducting sphere moving through a highly magnetized plasma of the companion's magnetosphere. Unusually, the interaction operates in a regime that is relativistic yet sub-Alfv\'{e}nic. Electromagnetic draping amplifies magnetic fields in a narrow layer near the stellar surface, leading to the generation of electric currents along the local magnetic field. The generation of beamed outflows enhances the instantaneous power of the pulsar-like radio and high-energy emission, produces spin/orbital modulations, and is likely to lead to observable precursor emission preceding the main gravitational wave event.