Gravitational and electromagnetic emission by magnetized coalescing binary systems

TL;DR

This paper explores how magnetic dipoles in coalescing binary systems can produce electromagnetic emissions alongside gravitational waves, with potential implications for observing short gamma-ray bursts.

Contribution

It introduces a model linking magnetic dipole evolution to electromagnetic and gravitational wave emissions in binary coalescence, providing quantitative estimates and observational constraints.

Findings

Electromagnetic emission can be comparable to gravitational wave emission for certain magnetic field strengths.

Magnetic dipole contributions can influence gravitational wave signals in neutron star mergers.

Energy outputs of electromagnetic and gravitational waves are similar under specific conditions.

Abstract

We discuss the possibility to obtain an electromagnetic emission accompanying the gravitational waves emitted in the coalescence of a compact binary system. Motivated by the existence of black hole configurations with open magnetic field lines along the rotation axis, we consider a magnetic dipole in the system, the evolution of which leads to (i) electromagnetic radiation, and (ii) a contribution to the gravitational radiation, the luminosity of both being evaluated. Starting from the observations on magnetars, we impose upper limits for both the electromagnetic emission and the contribution of the magnetic dipole to the gravitational wave emission. Adopting this model for the evolution of neutron star binaries leading to short gamma ray bursts, we compare the correction originated by the electromagnetic field to the gravitational waves emission, finding that they are comparable for particular values of the magnetic field and of the orbital radius of the binary system. Finally we calculate the electromagnetic and gravitational wave energy outputs which result comparable for some values of magnetic field and radius.