The essence of the Blandford-Znajek process

TL;DR

This paper demonstrates that the Blandford-Znajek process, a mechanism for extracting energy from rotating black holes, is kinematically equivalent to a Nambu-Goto string energy-extraction process, using a formalism linking electromagnetic fields and string dynamics.

Contribution

It introduces a formalism that relates force-free electromagnetic fields to string dynamics, revealing the kinematic equivalence of the Blandford-Znajek process and Nambu-Goto string energy extraction.

Findings

Force-free electromagnetic field sheets are equivalent to Nambu-Goto string world sheets.

The Blandford-Znajek process is kinematically identical to a string-based energy extraction.

The formalism provides new insights into black hole energy extraction mechanisms.

Abstract

From a spacetime perspective, the dynamics of magnetic field lines of force-free electromagnetic fields can be rewritten into a quite similar form for the dynamics of strings, i.e., dynamics of "field sheets". Using this formalism, we explicitly show that the field sheets of stationary and axisymmetric force-free electromagnetic fields have identical intrinsic properties to the world sheets of rigidly rotating Nambu-Goto strings. Thus, we conclude that the Blandford-Znajek process is kinematically identical to an energy-extraction mechanism by the Nambu-Goto string with an effective magnetic tension.