The distinguishing signature of Magnetic Penrose Process

TL;DR

This paper highlights that the Magnetic Penrose Process (MPP) can achieve over 100% efficiency in extracting rotational energy from black holes at low magnetic fields, surpassing previous understanding and comparing it to the Blandford-Znajek mechanism.

Contribution

It demonstrates that MPP can have super high efficiency at low magnetic fields, extending the understanding of energy extraction mechanisms from black holes beyond high magnetic field regimes.

Findings

MPP exceeds 100% efficiency at milli Gauss magnetic fields.

Blandford-Znajek mechanism operates efficiently at high magnetic fields (~10^4 G).

Simulation predictions suggest MPP can be highly efficient even at low magnetic fields.

Abstract

In this Letter, we wish to point out that the distinguishing feature of Magnetic Penrose process (MPP) is its super high efficiency exceeding $100\%$ (which was established in mid 1980s for discrete particle accretion) of extraction of rotational energy of a rotating black hole electromagnetically for a magnetic field of milli Gauss order. Another similar process, which is also driven by electromagnetic field, is Blandford-Znajek mechanism (BZ), which could be envisaged as high magnetic field limit MPP as it requires threshold magnetic field of order $10^4$G. Recent simulation studies of fully relativistic magnetohydrodynamic flows have borne out super high efficiency signature of the process for high magnetic field regime; viz BZ. We would like to make a clear prediction that similar simulation studies of MHD flows for low magnetic field regime, where BZ would be inoperative, would also have super efficiency.