Magnetic Reconnection and Energy Extraction from a Rotating Black Hole in a Four-dimensional Einstein-Gauss-Bonnet Gravity

Abstract

Recently, Comisso and Asenjo proposed a new mechanism for energy extraction based on magnetic reconnection of plasma within the ergosphere. In this paper, we analyze the power and efficiency of energy extraction through magnetic reconnection in a rotating four-dimensional Einstein-Gauss-Bonnet gravity black hole. Firstly, we analyze the background properties of this spacetime and its physical quantities, including the event horizon, the boundary of the ergosphere, and the size of the ergosphere. We analyze the magnetic reconnection in circular orbits and investigate the energy extraction region, as well as the power and efficiency of energy extraction. Our results indicate that energy extraction remains feasible even for a low spin parameter of $0.4$, which is well below the previously reported threshold. We also find that the energy extraction power exceeds that of the Blandford-Znajek mechanism. The Gauss-Bonnet coupling parameters $α$ lower the spin threshold for energy extraction. Similarly, we analyze the energy extraction region in the plunging regime, together with the corresponding power and efficiency. We find that energy extraction is possible even for a low spin parameter as $0.22$. We also observe that the Gauss-Bonnet coupling parameter $α$ further lowers the spin threshold. This behavior is consistent with that observed in the circular orbit case. Finally, we compare the energy extraction power in the plunging and circular orbit regimes and find that the plunging regime yields a higher energy extraction power than the circular orbit case.