Particle collisions and optical effects in the mining Kerr-Newman spacetimes

Abstract

We study ultra-high-energy particle collisions and optical effects in the extraordinary class of mining braneworld Kerr-Newman (KN) naked singularity spacetimes, predicting extremely high efficiency of Keplerian accretion, and compare the results to those related to the other classes of the KN naked singularity and black hole spacetimes. We demonstrate that in the mining KN spacetimes the ultra-high centre-of-mass energy occurs for collisions of particles following the extremely-lowenergy stable circular geodesics of the "mining regime", colliding with large family of incoming particles, e.g., those infalling from the marginally stable counter-rotating circular geodesics. This is qualitatively different situation in comparison to the standard KN naked singularity or black hole spacetimes where the collisional ultra-high centre-of-mass energy can be obtained only in the nearextreme spacetimes. We also show that observers following the stable circular geodesics of the mining regime can register extremely blue-shifted radiation incoming from the Universe, and see strongly deformed sky due to highly relativistic motion along such stable orbits. The strongly blue-shifted radiation could be thus a significant source of energy for such orbiting observers.

Seeing Black Holes: From the Computer to the Telescope

“…In the same line, ref. [18] calculated the appearance of a cosmic microwave background to observers orbiting in close vicinity of Kerr black holes or superspinars. As is well-known, the Kerr spacetime metric depends on two parameters, the black hole mass M and its normalized angular momentum a, but there is a critical angular momentum given by a = M (in units where G = c = 1) above which the event horizon vanishes, leaving a naked singularity, also called a Kerr superspinar.…”

“…In the same line, ref. [18] calculated the appearance of a cosmic microwave background to observers orbiting in close vicinity of Kerr black holes or superspinars. …”

Bounds on spinning particles in their innermost stable circular orbits around rotating braneworld black hole

“…Since the study of spinning particle dynamics has been done mostly in the context of Einstein's theory but scarcely for alternative theories of gravity, in this work we study the ISCO of a spinning massive test particle with arbitrary spin s in the vicinity of a rotating braneworld BH [76][77][78][79][80] which has an additional parameter C known as the braneworld tidal charge parameter in addition to the usual mass M and rotation a parameters.…”

Profiled spectral lines of Keplerian rings orbiting in the regular Bardeen black hole spacetimes

“…If the magnetic charge influence is restricted only on the uncharged matter through the accordingly modified spacetime geometry, its role is the same as of the electric charge [61,36]. Moreover, the RN spacetimes with the so called tidal charge are relevant in the braneworld Randall -Sundrum model [24] (possible astrophysical consequences of tidally charged black holes can be found in [1,39,65,55,56,18,41,19,34,72,75]). In the present paper we again construct for comparison also the profiled spectral lines, for the rings located at the same radii as those used in construction of profiled lines in the effective geometry, using the pure spacetime geometry (compare the results of [58]).…”