Acceleration of particles by quasiblack holes

TL;DR

This paper demonstrates that particles colliding near quasiblack holes can achieve unbounded center of mass energy without fine-tuning parameters, extending the known BSW effect from black holes to QBHs.

Contribution

It shows that the unbounded energy in particle collisions occurs in quasiblack hole spacetimes without the need for fine-tuning, unlike in black hole scenarios.

Findings

Unbounded CM energy can occur in QBH collisions without fine-tuning.

The effect applies to particles inside and outside the QBH.

QBH collisions can mimic the BSW effect near black holes.

Abstract

If two particles collide near the black hole horizon, the energy in the centre of mass (CM) frame can grow indefinitely (the so-called the BSW effect). This requires fine-tuning the parameters (the energy, angular momentum or electric charge) of one particle. We show that the CM energy can be unbound also for collisions in the space-time of quasiblack holes - QBHs (the objects on the threshold of forming the horizon which do not collapse). It does not require special fine-tuning of parameters and occurs when any particle inside a QBH having a finite energy collides with the particle that entered a QBH from the outside region.