Destinies of Plasmoids Formed from the Magnetic Reconnection Occurring within the Ergo Region of a Rotating Black Hole
Abstract
It is widely accepted that magnetic reconnections occur successively in black hole accretion flows, especially on the equatorial plane, owing to the formation of the equatorial current sheet. When magnetic reconnection takes place within the ergosphere of a rotating black hole, one of the ejected plasmoids (denoted as p-) may acquire negative energy-at-infinity density, while the companion plasmoid (denoted as p+) correspondingly carries the energy extracted from the black hole. This mechanism, known as the Comisso-Asenjo process, provides a viable astrophysical pathway for extracting energy from a rotating black hole. Generally speaking, two conditions have to be satisfied for successful energy extraction. First, p- is generated via magnetic reconnection with negative energy-at-infinity density. Second, the associated p+, which carries the extracted energy, must escape to infinity. Though a number of studies have promoted the theory of the Comisso-Asenjo process, the escape of p+ lacks consideration. In this work, we adopt geodesic approach to systematically examine the destinies of p+ after ejection, thereby establishing the complete conditions for energy extraction from a rotating black hole via magnetic reconnection. We redefine the covering factor, for which only escaping p+ are counted. This quantity reflects how probable the successful energy extraction occurs in an accretion system. Through analysis of this revised covering factor, we identify a lower bound on the black hole spin, a=0.8005, below which energy extraction via magnetic reconnection can never succeed, no matter how high the magnetization of the bulk plasma is. This limit suggests that the spin-down of a black hole caused by successive magnetic reconnections would terminate once the spin decreases to approximately 0.8005.
Related
- X-ray Polarization Signatures from Comptonization by Magnetic Reconnection Plasmoids
- The Birth of Plasmoids: Weibel-Driven Secondary Tearing and its Suppression in Relativistic Reconnection
- Energy extraction from NED-deformed rotating black holes via the Comisso-Asenjo reconnection process
- Three-dimensional magnetic reconnection in unipolar regions. A case study of coronal bright points in the Sun
- Current Sheets and Magnetic Reconnection statistics by Solar Orbiter at few to tens of Ion Inertial Lengths II: Conditions for Reconnection, and Current Sheet Planarity
BibTeX
@misc{yuchih2026destinies,
title = {{Destinies of Plasmoids Formed from the Magnetic Reconnection Occurring within the Ergo Region of a Rotating Black Hole}},
author = {Ho-Yun YuChih and Ye Shen},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.25097},
eprint = {2610.25097},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.25097},
}
RIS
TY - UNPB
TI - Destinies of Plasmoids Formed from the Magnetic Reconnection Occurring within the Ergo Region of a Rotating Black Hole
AU - Ho-Yun YuChih
AU - Ye Shen
PY - 2026
DA - 2026/10/18
PB - arXiv
DO - 10.48550/arxiv.2610.25097
UR - https://arxiv.org/abs/2610.25097
AB - It is widely accepted that magnetic reconnections occur successively in black hole accretion flows, especially on the equatorial plane, owing to the formation of the equatorial current sheet. When magnetic reconnection takes place within the ergosphere of a rotating black hole, one of the ejected plasmoids (denoted as p_-) may acquire negative energy-at-infinity density, while the companion plasmoid (denoted as p_+) correspondingly carries the energy extracted from the black hole. This mechanism, known as the Comisso-Asenjo process, provides a viable astrophysical pathway for extracting energy from a rotating black hole. Generally speaking, two conditions have to be satisfied for successful energy extraction. First, p_- is generated via magnetic reconnection with negative energy-at-infinity density. Second, the associated p_+, which carries the extracted energy, must escape to infinity. Though a number of studies have promoted the theory of the Comisso-Asenjo process, the escape of p_+ lacks consideration. In this work, we adopt geodesic approach to systematically examine the destinies of p_+ after ejection, thereby establishing the complete conditions for energy extraction from a rotating black hole via magnetic reconnection. We redefine the covering factor, for which only escaping p_+ are counted. This quantity reflects how probable the successful energy extraction occurs in an accretion system. Through analysis of this revised covering factor, we identify a lower bound on the black hole spin, a=0.8005, below which energy extraction via magnetic reconnection can never succeed, no matter how high the magnetization of the bulk plasma is. This limit suggests that the spin-down of a black hole caused by successive magnetic reconnections would terminate once the spin decreases to approximately 0.8005.
ER -