Maximum possible energies of electrons accelerated in magnetospheres of rotating black holes

TL;DR

This paper evaluates the maximum energies electrons can attain in black hole magnetospheres, considering various black hole masses and limiting physical mechanisms, revealing how these energies depend on black hole properties.

Contribution

It models electron acceleration in rotating magnetic fields around black holes, incorporating multiple limiting factors to determine maximum attainable Lorentz factors across different black hole types.

Findings

Electrons reach Lorentz factors up to 10^6 in ultra-massive black holes.

Maximum energies vary significantly with black hole mass and spin.

Different physical constraints dominate the maximum energy limits depending on black hole category.

Abstract

Our aim is to evaluate the maximum attainable energies of electrons accelerated by means of the magneto-centrifugal mechanism. We examine how the range of maximum possible energies, as well as the primary limiting factors, vary with black hole mass. Additionally, we analyse the dependence of the maximum relativistic factor on the initial distance from the black hole and its spin factor in the range 0.1 - 0.2. We model the acceleration of electrons on rotating magnetic field lines and apply several constraining mechanisms: the inverse Compton scattering, curvature radiation, and the breakdown of the bead-on-the-wire approximation. As a result, the maximum Lorentz factors for electron acceleration vary with the type of black hole. For stellar-mass black holes, electrons can be accelerated up to the Lorentz factors 1.3 * 10^3 - 1.3 * 10^4 with only co-rotation constrain affecting the maximum relativistic factor; In intermediate-mass black holes, the Lorentz factors are in the interval 1.3 * 10^4 - 1.1 * 10^5; For the supermassive black holes the Lorentz factors range from 7 * 10^4 to 1.7 * 10^5; while the ultra-massive black hole located at the center of Abell 1201 can accelerate electrons up to 10^6 with both the co-rotation and Inverse Compton in Thomson regime determining the final Lorentz factor for the last three categories.