An elementary particle model with Bertotti-Robinson core

Abstract

Spherically symmetric classical model of an elementary particle or a black hole spacetime without central singularity had been constructed by O. B. Zaslavskii, Classical model of an elementary particle with a Bertotti-Robinson core and extremal black holes, Phys. Rev. D 70 (2004) 104017. In this model, an extremal Reissner-Nordstrom (RN) black hole and a Bertotti-Robinson (BR) spacetime are glued at the horizon such that the inner/core spacetime is the regular BR while outside is the extremal RN. The fact that near horizon geometry of the extremal RN coincides with BR spacetime becomes helpful in the construction. We investigate the stability of such a particle/regular black hole against linear radial perturbations. The model turns out to be stable against such perturbations with a linear equation of state for a perfect fluid after the perturbation. To complete our study, we give a generic particle model whose inner and outer metrics must satisfy more general conditions.