Spinning Black Holes as Particle Accelerators

TL;DR

This paper explains how spinning black holes can theoretically accelerate particles to extremely high energies but discusses practical limitations that prevent such ultra-energetic collisions from occurring naturally.

Contribution

It clarifies the mechanism behind high-energy particle collisions near Kerr black holes and highlights the limitations preventing these from happening in real astrophysical scenarios.

Findings

Particles can collide with arbitrarily high energy near maximally spinning black holes.

Practical limitations prevent ultra-energetic collisions in natural settings.

Theoretical mechanism differs from realistic astrophysical conditions.

Abstract

It has recently been pointed out that particles falling freely from rest at infinity outside a Kerr black hole can in principle collide with arbitrarily high center of mass energy in the limiting case of maximal black hole spin. Here we aim to elucidate the mechanism for this fascinating result, and to point out its practical limitations, which imply that ultra-energetic collisions cannot occur near black holes in nature.