Energy extraction from electrovacuum black holes via production of pairs of oppositely charged particles

TL;DR

The paper addresses energy extraction from electrovacuum black holes via collisions that produce oppositely charged particle pairs. It develops a formal algebraic framework for momentum conservation in stationary, axisymmetric spacetimes, showing that the post-collision momenta lie on an ellipse and that the centre-of-mass energy $E_\mathrm{c.m.}$ bounds the masses of produced particles. By considering near-horizon, neutral-initial collisions with large charge-to-mass ratios for the final particles, it demonstrates that one fragment can escape with energy $E_3 \sim q_3Q/r_C$ and efficiency $\eta \sim q_3Q/(m_3M)$ without requiring black-hole extremality or fine-tuning. The results highlight a robust mechanism for high-energy extraction enabled by electromagnetic interaction in electrovacuum Kerr-Newman spacetimes, with potentially huge efficiencies for suitably charged final states.

Abstract

We consider collisional Penrose process for charged, rotating black holes together with a simple model of pair creation, in which two oppositely charged particles are produced in a collision of two neutral particles. We highlight that significant energy extraction is possible without assuming fine-tuning or extremality as long as the escaping particles are sufficiently charged.