Extracting the energy and angular momentum of a Kerr black hole

J. A. Rueda; R. Ruffini

doi:10.1140/epjc/s10052-023-12153-y

2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2023) 83: 960
https://doi.org/10.1140/epjc/s10052-023-12153-y

Regular Article - Theoretical Physics

Extracting the energy and angular momentum of a Kerr black hole

J. A. Rueda¹^,2^,3^,4^,5^a and R. Ruffini¹^,2^,6

¹ ICRANet, Piazza della Repubblica 10, 65122, Pescara, Italy
² ICRA, Dipartimento di Fisica, Sapienza Università di Roma, P.le Aldo Moro 5, 00185, Rome, Italy
³ ICRANet-Ferrara, Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Ferrara, Via Saragat 1, 44122, Ferrara, Italy
⁴ Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Ferrara, Via Saragat 1, 44122, Ferrara, Italy
⁵ INAF, Istituto de Astrofisica e Planetologia Spaziali, Via Fosso del Cavaliere 100, 00133, Rome, Italy
⁶ INAF, Viale del Parco Mellini 84, 00136, Rome, Italy

^a jorge.rueda@icra.it

Received: 4 September 2023
Accepted: 14 October 2023
Published online: 24 October 2023

Abstract

It has been thought for decades that rotating black holes (BHs) power the energetic gamma-ray bursts (GRBs) and active galactic nuclei (AGNs), but the mechanism that extracts the BH energy has remained elusive. We here show that the solution to this problem arises when the BH is immersed in an external magnetic field and ionized low-density matter. For a magnetic field parallel to the BH spin, the induced electric field accelerates electrons outward and protons inward in a conical region, centered on the BH rotation axis, and of semi-aperture angle $θ \approx 60^{\circ}$ $\theta \approx 60^\circ$ from the BH rotation axis. For an antiparallel magnetic field, protons and electrons exchange their roles. The particles that are accelerated outward radiate off energy and angular momentum to infinity. The BH powers the process by reducing its energy and angular momentum by capturing polar protons and equatorial electrons with net negative energy and angular momentum. The electric potential allows for negative energy states outside the BH ergosphere, so the latter does not play any role in this electrodynamical BH energy extraction process.

© The Author(s) 2023

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