Motion of charged test particles in Reissner--Nordstr\"om spacetime

We investigate the circular motion of charged test particles in the gravitational field of a charged mass described by the Reissner-Nordstr\"om (RN) spacetime. We study in detail all the spatial regions where circular motion is allowed around either black holes or naked singularities. The effects of repulsive gravity are discussed by finding all the circles at which a particle can have vanishing angular momentum. We show that the geometric structure of stable accretion disks, made of only test particles moving along circular orbits around the central body, allows us to clearly distinguish between black holes and naked singularities.Comment: 58 pages, 41 figures. To be published in Phys. Rev. D. This work follows the paper "Circular motion of neutral test particles in Reissner-Nordstr\'om spacetime" published in Phys.\ Rev.\ D \ Vol.83, No.2 with DOI: 10.1103/PhysRevD.83.024021 (arXiv:1012.5411v1 [astro-ph.HE]

Is there life inside black holes?

Bound inside rotating or charged black holes, there are stable periodic planetary orbits, which neither come out nor terminate at the central singularity. Stable periodic orbits inside black holes exist even for photons. These bound orbits may be defined as orbits of the third kind, following the Chandrasekhar classification of particle orbits in the black hole gravitational field. The existence domain for the third kind orbits is rather spacious, and thus there is place for life inside supermassive black holes in the galactic nuclei. Interiors of the supermassive black holes may be inhabited by civilizations, being invisible from the outside. In principle, one can get information from the interiors of black holes by observing their white hole counterparts.Comment: 11 pages, 5 figures; references adde

General classification of charged test particle circular orbits in Reissner–Nordström spacetime

Abstract We investigate charged particles’ circular motion in the gravitational field of a charged mass distribution described by the Reissner–Nordström spacetime. We introduce a set of independent parameters completely characterizing the different spatial regions in which circular motion is allowed. We provide a most complete classification of circular orbits for different sets of particle and source charge-to-mass ratios. We study both black holes and naked singularities and show that the behavior of charged particles depend drastically on the type of source. Our analysis shows in an alternative manner that the behavior of circular orbits can in principle be used to distinguish between black holes and naked singularities. From this analysis, special limiting values for the dimensionless charge of black hole and naked singularity emerge, namely, Q/M $$=$$ = 1/2, $$Q/M=\sqrt{13}/5$$ Q / M = 13 / 5 and $$Q/M=\sqrt{2/3}$$ Q / M = 2 / 3 for the black hole case and Q/M $$=$$ = 1, $$Q/M=5/ (2 \sqrt{6})$$ Q / M = 5 / ( 2 6 ) , $$Q/M=3 \sqrt{6}/7$$ Q / M = 3 6 / 7 , and finally $$Q/M= \sqrt{9/8}$$ Q / M = 9 / 8 for the naked singularity case. Similarly and surprisingly, analogous limits emerge for the orbiting particles charge-to-mass ratio $$\epsilon$$ ϵ , for positive charges $$\epsilon =1$$ ϵ = 1 , $$\epsilon =2$$ ϵ = 2 and $$\epsilon =M/Q$$ ϵ = M / Q . These limits play an important role in the study of the coupled electromagnetic and gravitational interactions, and the investigation of the role of the charge in the gravitational collapse of compact objects