Energy Extraction via Magnetic Reconnection in Kerr-Sen-AdS$_{4}$ Black Hole: Circular Plasma and Plunging Plasma

TL;DR

This study analyzes magnetic reconnection as a mechanism for energy extraction from Kerr-Sen-AdS4 black holes, revealing conditions under which it surpasses the Blandford-Znajek process and how parameters influence the energy extraction thresholds.

Contribution

It introduces a detailed comparison of energy extraction via magnetic reconnection in different regions of Kerr-Sen-AdS4 black holes, highlighting the effects of scalar charge and AdS radius on thresholds.

Findings

Energy extraction feasible at spin as low as 0.5, below previous thresholds.

Extracted power can exceed Blandford-Znajek mechanism under certain conditions.

Plunging region shows higher power and efficiency than circular orbit region.

Abstract

In this paper, we investigate the power and efficiency of energy extraction through magnetic reconnection in the Kerr-Sen-AdS$_{4}$ black hole, with a primary focus on both the circular orbit and plunging region. We plot the allowed regions for energy extraction and present corresponding power and efficiency values, comparing them with those of the Blandford-Znajek (BZ) mechanism. Our analysis reveals that energy extraction remains feasible even at a spin parameter as low as 0.5, significantly below previously reported thresholds, and the extracted power can exceed that of the BZ process under certain conditions. Furthermore, the dilatonic scalar charge $b$ and the AdS radius $l$ collectively contribute to lowering the spin threshold for energy extraction. The energy extraction process in the plunging region was further examined by analyzing the permissible energy extraction region, as well as the corresponding power output and efficiency. One can find that the energy extraction is possible even at a spin as low as 0.25. Crucially, parameter $b$ actively lowers the energy extraction spin threshold, while parameter $l$ exerts a counteracting effect, impeding such reduction. This trend shows a marked contrast with circular orbit behavior. Additionally, both power and efficiency in the plunging region consistently surpass those in the circular orbit region, indicating superior energy extraction capability in plunging region.