General relativistic simulations of binary black hole-neutron stars: Precursor electromagnetic signals

TL;DR

This paper presents the first general relativistic force-free simulations of neutron star magnetospheres orbiting black holes, revealing promising electromagnetic precursor signals that could serve as observable indicators of such systems.

Contribution

It introduces novel simulations of NS-BH systems in full general relativity, highlighting electromagnetic emissions and beaming effects not previously modeled.

Findings

Poynting luminosities up to 6 x 10^{42} erg/s at specific orbital separations

Electromagnetic flux peaks within a broad beam, suggesting lighthouse-like emission

Preliminary results indicate detectable precursor signals before merger

Abstract

We perform the first general relativistic force-free simulations of neutron star (NS) magnetospheres in orbit about spinning and non-spinning black holes. We find promising precursor electromagnetic emission: typical Poynting luminosities at, e.g., an orbital separation of 6.6 times the NS radius are L ~ 6 x 10^{42} erg/s for a 1.4 solar-mass NS with a 10^{13}G polar magnetic field. The Poynting flux peaks within a broad beam of ~40 degrees in the azimuthal direction and within ~60 degrees from the orbital plane, establishing a possible lighthouse effect. Our calculations, though preliminary, preview more detailed simulations of these systems that we plan to perform in the future.