Acceleration of particles in spacetimes of black string

Abstract

The particle acceleration mechanism in $S^2 \times\mathbb{R}^1$ topology, namely in the spacetime of the five-dimensional compact black string has been studied. The expression of center-of-mass energy of the colliding neutral particles near static black string has been found. The collision of charged particle moving at the innermost stable circular orbit with neutral particle coming from infinity have been considered when black string is immersed in external uniform magnetic field. It has been shown that the unlimited center-of-mass energy can be approached in case of the extremal rotation of the black string which is similar to the analogous effect in the Kerr spacetime. We have also obtained that the scattering energy of particles in the center-of-mass system can take arbitrary large values not only for extremal black string but also for nonextremal one. It has been derived that the presence of the extra dimension can, in principle, increase the upper limit of efficiency of energy extraction from the extremely rotating black string up to $203\%$ versus to $143\%$ which can be extracted from the extreme Kerr black hole.