"Kerrr" black hole: the Lord of the String

Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Trieste, Italy
Physics Letters B (Impact Factor: 6.13). 04/2010; 688(1):82-87. DOI: 10.1016/j.physletb.2010.03.075
Source: arXiv


Kerrr in the title is not a typo. The third “r” stands for regular, in the sense of pathology-free rotating black hole. We exhibit a long search-for, exact, Kerr-like, solution of the Einstein equations with novel features: (i) no curvature ring singularity; (ii) no “anti-gravity” universe with causality violating time-like closed world-lines; (iii) no “super-luminal” matter disk.The ring singularity is replaced by a classical, circular, rotating string with Planck tension representing the inner engine driving the rotation of all the surrounding matter.The resulting geometry is regular and smoothly interpolates among inner Minkowski space, borderline de Sitter and outer Kerr universe. The key ingredient to cure all unphysical features of the ordinary Kerr black hole is the choice of a “non-commutative geometry inspired” matter source as the input for the Einstein equations, in analogy with spherically symmetric black holes described in earlier works.

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    • "Instead of using a complete NC description of black holes we follow a method used in [18] -NC theory is used only to obtain the energy density of the black hole, rest of the study is done using the classical theory (this is dubbed as NC inspired black holes). More details on NC inspired cosmology and gravity could be found in [1] [2] [17] [19] [20] [23] [27]. "
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    ABSTRACT: We study black holes with a source that is almost point-like (blurred), rather than exactly point-like, which could be caused by the noncommutativity of 3-space. Depending on its mass, such object has either none, one or two event horizons. It possesses new properties, which become important on microscopic scale, in particular the temperature of its Hawking radiation does not increase infinitely as its mass goes to zero, but vanishes instead. Such frozen, extremely dense pieces of matter are good dark matter candidate. In addition, we introduce an object oscillating between frozen black hole and naked (softened) singularity, such objects can serve as constituents of dark matter too. We call it gravimond.
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    • "The UV finiteness of any non-local theory like that in (11) is guaranteed at any order only for a certain degree of convergence of the entire function A. According to the definition given in [62] [63], such a global convergence occurs for entire functions of order higher than 1/2. As an example, NCG inspired black holes [17] [18] [19] [64] [65] [66] [67] [68] [69] and the associated quantum field theory [70] [71] [72] are non-local formulations employing such a kind of entire function [20]. At the level of free fields the convergence is achieved also in the case of order 1/2. "

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    • "The above profile cures the usual Dirac delta (singular) distribution associated to a pointparticle , and leads to a family of regular black hole solutions [19] [20] [21] [22] [23] [24] [25] [26] [27] [28]. "
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    ABSTRACT: In the presence of a minimal length physical objects cannot collapse to an infinite density, singular, matter point. In this note we consider the possible final stage of the gravitational collapse of "thick" matter layers. The energy momentum tensor we choose to model these shell-like objects is a proper modification of the source for "non-commutative geometry inspired", regular black holes. By using higher momenta of Gaussian distribution to localize matter at finite distance from the origin, we obtain new solutions of the Einstein's equation which smoothly interpolates between Minkowski geometry near the center of the shell and Schwarzschild spacetime far away from the matter layer. The metric is curvature singularity free. Black hole type solutions exist only for "heavy" shells, i.e. $M\ge M_{e}$, where $M_{e}$ is the mass of the extremal configuration. We determine the Hawking temperature and a modified Area Law taking into account the extended nature of the source.
    Advances in High Energy Physics 10/2011; 2013. DOI:10.1155/2013/812084 · 2.20 Impact Factor
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