Wormholes and nonsingular spacetimes in Palatini f(R) gravity
Cosimo Bambi, Alejandro Cardenas-Avendano, Gonzalo J. Olmo, and D. Rubiera-Garcia
Phys. Rev. D 93, 064016 – Published 7 March 2016
Abstract: We reconsider the problem of f(R) theories of gravity coupled to Born-Infeld theory of electrodynamics formulated in a Palatini approach, where metric and connection are independent fields. By studying electrovacuum configurations in a static and spherically symmetric spacetime, we find solutions which reduce to their Reissner-Nordström counterparts at large distances but undergo important nonperturbative modifications close to the center. Our new analysis reveals that the pointlike singularity is replaced by a finite-size wormhole structure, which provides a geodesically complete and thus nonsingular spacetime, despite the existence of curvature divergences at the wormhole throat. Implications of these results, in particular for the cosmic censorship conjecture, are discussed.