On the particle collisions during gravitational collapse of Vaidya spacetimes

TL;DR

This paper investigates high-energy particle collisions near the boundary of a collapsing Vaidya spacetime, revealing that unbounded center-of-mass energy can occur near the conformal Killing horizon during gravitational collapse.

Contribution

It demonstrates that in Vaidya spacetimes with naked singularities, particle collisions can achieve arbitrarily high energies near the conformal Killing horizon, extending previous Schwarzschild results.

Findings

Center-of-mass energy diverges near the conformal Killing horizon.

High-energy collisions occur when particles collide near the boundary of the collapsing cloud.

Unbounded energy is possible during gravitational collapse in Vaidya spacetime.

Abstract

The center-of-mass energy can be arbitrarily high in Schwarzschild spacetime if one considers the front collision of two particles, one of which moves along so-called white hole geodesics and another one along a black hole geodesic. This process can take place if one considers the gravitational collapse model. In this paper, we consider the well-known naked singularity formation in Vaidya spacetime and investigate the question about two particle collision near the boundary of the collapsing cloud. The center-of-mass energy of the front collision is considered. One particle moves away from the naked singularity and another one falls onto a collapsing cloud. We show that the center-of-mass energy grows unboundly if the collision takes place in the vicinity of the conformal Killing horizon.