Electromagnetic extraction of energy from merging black holes

TL;DR

This paper models the electromagnetic energy output generated by merging black holes, showing how their interaction with magnetic fields can produce observable electromagnetic signals during the merger.

Contribution

It provides a quantitative calculation of the electromagnetic power generated by merging black holes via a Blandford-Znajek-type process, linking gravitational dynamics to electromagnetic emissions.

Findings

Electromagnetic luminosity can reach 10^{37}-10^{39} erg/s during mergers.

Generated emissions include variable collimated jets and broad-band isotropic signals.

The model predicts observable electromagnetic signatures associated with black hole mergers.

Abstract

We calculate the evolution of the prompt intrinsic Poynting power generated by merging black holes. Orbiting black holes induce rotation of the space-time. In a presence of magnetic field supported by an accretion disk outside of the orbit, this results in a generation of an electromagnetic outflow via the Blandford-Znajek-type process with luminosity $L_{EM} \sim G^3 M^3 B^2/(c^5 R_{orb}) $ and reaching a fairly low maximum values of $L_{EM} = 10^{37}-10^{39} m_6 $ erg s$^{-1}$ ($m_6$ is the masses of black holes in millions of Solar mass) at the time of the merger. Dissipation of the wind power may produce two types of observed signatures: a highly variable collimated emission coming from the internal dissipation within the jets and a broad-band near-isotropic emission generated at the termination shocks.