Weakly magnetized black holes as particle accelerators

TL;DR

This paper investigates how weak magnetic fields around non-rotating black holes can enable high-energy particle collisions near the horizon, highlighting potential but limited astrophysical acceleration effects.

Contribution

It reveals that magnetic fields can position charged particles close to the horizon for high-energy collisions, a novel insight into black hole particle acceleration mechanisms.

Findings

High collision energies possible near weakly magnetized black holes

ISCO of charged particles can be close to the horizon due to magnetic fields

Realistic black holes have limited capacity as particle accelerators

Abstract

We study collision of particles in the vicinity of a horizon of a weakly magnetized non-rotating black hole. In the presence of the magnetic field innermost stable circular orbits (ISCO) of charged particles can be located close to the horizon. We demonstrate that for a collision of two particles, one of which is charged and revolving at ISCO and the other is neutral and falling from infinity, the maximal collision energy can be high in the limit of strong magnetic field. This effect has some similarity with the recently discussed effect of high center-of-mass energy for collision of particles in extremely rotating black holes. We also demonstrate that for `realistic' astrophysical black holes their ability to play the role of `accelerators' is in fact quite restricted.