Abstract
We investigate possible signatures of a Kerr naked singularity (superspinar) in various observational phenomena. It has been shown that Kerr naked singularities (superspinars) have to be efficiently converted to a black hole due to accretion from Keplerian discs. In the final stages of the conversion process the near-extreme Kerr naked singularities (superspinars) provide a variety of extraordinary physical phenomena. Such superspinning Kerr geometries can serve as an efficient accelerator for extremely high-energy collisions, enabling a direct and clear demonstration of the outcomes of the collision processes. We shall discuss the efficiency and the visibility of the ultra-highenergy collisions in the deepest parts of the gravitational well of superspinning near-extreme Kerr geometries for the whole variety of particles freely falling from infinity. We demonstrate that ultrahigh-energy processes can be obtained with no fine tuning of the motion constants and the products of<br />the collision can escape to infinity with efficiency substantially higher than in the case of near-extreme black holes. Such phenomena influence the radiative processes taking place in the accretion disc, and together with the particular generated geometry they influence the observed radiation field. Here we<br />assume the “geometrical” influence of a Kerr naked singularity on the spectral line profiles of radiation emitted by monochromatically and isotropically radiating point sources forming a Keplerian ring or disc around such a compact object. We have found that the profiled spectral line of the radiating<br />Keplerian ring can be split into two parts because there is no event horizon in the naked singularity spacetimes. The profiled lines generated by Keplerian discs are qualitatively different for a Kerr naked singularity and black hole spacetimes broadened near the inner edge of a Keplerian disc.
Highlights
String Theory, one of the most relevant candidates for the theory of all physical interactions and quantum gravity, indicates a possibility to be tested in relativistic astrophysics
It is assumed that the spacetime outside a Kerr superspinar of radius R, where the stringy effects are irrelevant, is described by the standard Kerr geometry
The exact solution describing the interior of the superspinar is not yet known in the 3+1 theory, but it is considered that its extension is limited to 0 < R < M covering the region of causality violations and physical singularity and still allowing for the presence of the most interesting astrophysical phenomena related to the Kerr naked singularity spacetimes [1]; we assume here R = 0
Summary
String Theory, one of the most relevant candidates for the theory of all physical interactions and quantum gravity, indicates a possibility to be tested in relativistic astrophysics. Gimon and Hořava [1] have shown that Kerr superspinars with mass M and angular momentum J violating the general relativistic limit on the spin of black holes (a = J/M 2 > 1) could be primordial remnants of the high-energy phase of a very early period in the evolution of the Universe, when the effects of String Theory were relevant. The exact solution describing the interior of the superspinar is not yet known in the 3+1 theory, but it is considered that its extension is limited to 0 < R < M covering the region of causality violations (naked time machine) and physical singularity and still allowing for the presence of the most interesting astrophysical phenomena related to the Kerr naked singularity spacetimes [1]; we assume here R = 0. The properties of the surface of Kerr superspinars are usually assumed to correspond to those of the black hole horizon, i.e., the surface is assumed to serve as a one-way membrane. We assume for simplicity surface properties resembling those of the black hole horizon
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
