Particle acceleration driven by null electromagnetic fields near a Kerr black hole

TL;DR

This paper investigates how null electromagnetic fields near a Kerr black hole can rapidly accelerate particles to relativistic energies, potentially explaining observed high-energy flares.

Contribution

It introduces a model of particle acceleration driven by null electromagnetic fields in the vicinity of Kerr black holes, highlighting rapid energy gain mechanisms.

Findings

Particles can be instantaneously accelerated to relativistic speeds.

Maximum proton energy estimated at around 100 TeV near supermassive black holes.

The model explains high-energy flares observed in black hole systems.

Abstract

Short timescale variability is often associated with a black hole system. The consequence of an electromagnetic outflow suddenly generated near a Kerr black hole is considered assuming that it is described by a solution of a force-free field with a null electric current. We compute charged particle acceleration induced by the burst field. The interaction between the particle and the field is characterized by a large dimensionless number. We show that the particle is instantaneously accelerated to the relativistic regime by the field with a very large amplitude. The typical maximum energy attained by a proton for an event near a super massive black hole is $E_{\rm max} \sim 100$ TeV, which is enough observed high-energy flares.