Self-consistent multidimensional Penrose process driven by magnetic reconnection

TL;DR

This paper develops a multidimensional formalism to study plasmoid-driven Penrose processes in black hole environments, incorporating reconnection effects beyond the equatorial plane and connecting with numerical simulations.

Contribution

It introduces a general approach to analyze plasmoid-driven Penrose processes in curved, multidimensional settings, extending previous equatorial plane studies and linking with simulation data.

Findings

Existence of an ergobelt as a natural reconnection site.

Conditions for energetic viability of plasmoid-driven Penrose processes.

Application to matter- and magnetic-field-dominated scenarios.

Abstract

Astronomical observations and numerical simulations are providing increasing evidence that resistive effects in plasmas around black holes play an important role in determining the phenomenology observed from these objects. In this spirit, we present a general approach to the study of a Penrose process driven by plasmoids that are produced at reconnection sites along current sheets. Our formalism is meant to determine the physical conditions that make a plasmoid-driven Penrose process energetically viable and can be applied to scenarios that are matter- or magnetic-field-dominated, that is, in magnetohydrodynamical or force-free descriptions. By exploring reconnection from an axisymmetric but curved surface, our approach can be considered genuinely multidimensional and allows us to explore conditions that are beyond the ones explored so far and that have been restricted to the equatorial plane. Furthermore, it provides a direct contact with numerical simulations of accretion onto black holes, which exhibit an intense reconnection activity outside the equatorial plane. Finally, to describe the kinematics of the plasma self-consistently, we use the well-known configuration of an equilibrium torus with a purely toroidal magnetic field. For such a torus, we discuss the existence of an ``ergobelt'', \ie a nontrivial surface penetrating the ergosphere and acting as a natural a site for the occurrence of reconnection, and from where we estimate the energetics of a plasmoid-driven Penrose process.