Eur. Phys. J. C (2012) 72: 2098
https://doi.org/10.1140/epjc/s10052-012-2098-7

Regular Article - Theoretical Physics

Nonsingular black holes in quadratic Palatini gravity

¹ Departamento de Física Teórica and IFIC, Centro Mixto Universidad de Valencia-CSIC, Universidad de Valencia, Burjassot, 46100, Valencia, Spain
² Departamento de Física, Universidad de Oviedo, Avenida Calvo Sotelo 18, 33007, Oviedo, Asturias, Spain

^* e-mail: rubieradiego@gmail.com

Received: 18 May 2012
Revised: 24 June 2012
Published online: 7 August 2012

Abstract

We find that if general relativity is modified at the Planck scale by a Ricci-squared term, electrically charged black holes may be nonsingular. These objects concentrate their mass in a microscopic sphere of radius , where l _P is the Planck length and N _q is the number of electric charges. The singularity is avoided if the mass of the object satisfies the condition , where m _P is the Planck mass and α _em is the fine-structure constant. For astrophysical black holes this amount of charge is so small that their external horizon almost coincides with their Schwarzschild radius. We work within a first-order (Palatini) approach.