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Centro de Astrofísica da Universidade do Porto

Wormholes and nonsingular spacetimes in Palatini f (R) gravity

C. Bambi, A. Cardenas-Avendano, G. J. Olmo, D. Rubiera-Garcia

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.

Physical Review D
Volume 93
March 2016

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