ACCELERATION OF PARTICLES BY QUASIBLACK HOLES

Abstract

If two particles collide near the black hole horizon, the energy in their center of mass (CM) frame can grow indefinitely (the so-called Bañados, Silk and West (BSW) effect). This requires fine-tuning the parameters (the energy–momentum, angular momentum or electric charge) of one particle. We show that the CM energy can be unbound also for collisions in the spacetime 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.