Energy extraction through magnetic reconnection from a Kerr-Newman black hole in perfect fluid dark matter

TL;DR

This paper investigates how magnetic reconnection can extract energy from a Kerr-Newman black hole in a perfect fluid dark matter environment, revealing optimal conditions for energy extraction that do not require near-extremal black hole spins.

Contribution

It introduces a detailed analysis of energy extraction via magnetic reconnection in Kerr-Newman black holes within dark matter backgrounds, highlighting the influence of dark matter parameters on efficiency.

Findings

Horizon and ergoregion size vary non-monotonically with dark matter parameter λ.

Optimal combinations of black hole parameters enhance energy extraction efficiency.

High energy extraction can be achieved without near-extremal black hole spins.

Abstract

In this work, we provide a thorough analysis of energy extraction via magnetic reconnection, a novel mechanism recently proposed by Comisso and Asenjo, for a Kerr-Newman black hole immersed in a perfect fluid dark matter (PFDM) background. Our studies focus on the impact of black hole spin $a$, electric charge $Q$ and PFDM parameter $\lambda$ on the horizons, ergoregion and circular geodesics at the equatorial plane of this black hole, and how they further influence the reconnection efficiency and energy extraction rate. Our results show that the outer horizon and the size of ergoregion do not vary monotonically with increasing dark matter parameters $\lambda$ until reaching its critical value $\lambda_c$ due to the combined counteracting effect between the black hole's charge and dark matter parameter. We identify the optimal combinations of $a$, $Q$ and $\lambda$ that allow for efficient energy extraction and high extracted power, even when the black hole is not spinning near its extremal limit. Our results ease the stringent conditions observed in other rotating black holes, where achieving comparable levels of extracted power and reconnection efficiency typically requires a near-extremal spin.