1112.0475 (Gonzalo J. Olmo et al.)

Nonsingular black holes in quadratic Palatini gravity    [PDF]

Gonzalo J. Olmo, D. Rubiera-Garcia

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 $r_{core}\approx N_q^{1/2}l_P/3$, 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 $M_0^2\approx m_P^2 \alpha_{em}^{3/2} N_q^3/2$, where $m_P$ is the Planck mass and $\alpha_{em}$ 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.

View original: http://arxiv.org/abs/1112.0475