Magnetized Neutron Star Mergers and Gravitational Wave Signals

TL;DR

This paper explores how magnetic fields affect neutron star merger dynamics and gravitational wave signals, revealing magnetic phenomena that influence both electromagnetic and gravitational wave emissions.

Contribution

It presents the first full general relativity MHD simulations of magnetized neutron star mergers, highlighting magnetic effects on merger timing and gravitational waveforms.

Findings

Magnetic fields delay the final merger.

Magnetic phenomena influence gravitational wave signals.

Magnetic effects induce electromagnetic radiation.

Abstract

We investigate the influence of magnetic fields upon the dynamics of and resulting gravitational waves from a binary neutron star merger in full general relativity coupled to ideal magnetohydrodynamics (MHD). We consider two merger scenarios, one where the stars begin with initially aligned poloidal magnetic fields and one with no magnetic field. Both mergers result in a strongly differentially rotating object. In comparison to the non-magnetized scenario, the aligned magnetic fields delay the final merger of the two stars. During and after merger we observe phenomena driven by the magnetic field, including Kelvin-Helmholtz instabilities in shear layers, winding of the field lines, and transition from poloidal to toroidal fields. These effects not only produce electromagnetic radiation, but also can have a strong influence on the gravitational waves. Thus, there are promising prospects for studying such systems with both types of waves.