scholarly journals The centre-of-mass energy of two colliding particles in STU black holes

2014 ◽  
Vol 92 (12) ◽  
pp. 1562-1564 ◽  
Author(s):  
Hassan Saadat
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Maximum Energy ◽  
Black Hole Horizon ◽  
Charged Black Hole ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Hole Charge ◽  
Stu Black Hole

In this paper we consider the collision of two particles near an STU black hole and calculate the centre-of-mass energy. In the case of an uncharged black hole we find that the maximum energy occurs near the black hole horizon, similar to the case of a charged black hole. We confirm that black hole charge decreases the centre-of-mass energy near the black hole horizon.

scholarly journals Quantum gravity on the black hole horizon

2022 ◽  
Vol 2022 (1) ◽  
Author(s):  
Nava Gaddam ◽  
Nico Groenenboom ◽  
Gerard ’t Hooft
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Flat Space ◽  
Scattering Matrix ◽  
Black Hole Horizon ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Gravitational Effects ◽  
Classical Black Holes ◽  
Schwarzschild Radius

Abstract We study scattering on the black hole horizon in a partial wave basis, with an impact parameter of the order of the Schwarzschild radius or less. This resembles the strong gravity regime where quantum gravitational effects appear. The scattering is governed by an infinite number of virtual gravitons exchanged on the horizon. Remarkably, they can all be summed non-perturbatively in ħ and γ ∼ MPl/MBH. These results generalise those obtained from studying gravitational backreaction. Unlike in the eikonal calculations in flat space, the relevant centre of mass energy of the collisions is not necessarily Planckian; instead it is easily satisfied, s » γ2$$ {M}_{\mathrm{Pl}}^2 $$ M Pl 2 , for semi-classical black holes. The calculation lends further support to the scattering matrix approach to quantum black holes, and is a second-quantised generalisation of the same.

R-N black holes can be transformed into K-N black holes

2021 ◽  
Author(s):  
Wen-Xiang Chen
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Angular Momentum ◽  
Boundary Conditions ◽  
Black Hole Entropy ◽  
Charged Black Hole ◽  
Naked Singularities ◽  
Hole Charge

If there is no strong cosmic supervision conjecture, there may be naked singularities. The decrease in black hole entropy indicates that there is periodicity inside the black hole.This article points out that when the entropy of a black hole decreases, its enthalpy will increase, and the black hole charge will be converted into angular momentum through a certain channel. This article hereby asserts that a non-rotating charged black hole will transform into a rotating charged black hole under the effect of superradiation under preset boundary conditions.

scholarly journals New non-extremal and BPS hairy black holes in gauged $$ \mathcal{N} $$ = 2 and $$ \mathcal{N} $$ = 8 supergravity

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Andres Anabalon ◽  
Dumitru Astefanesei ◽  
Antonio Gallerati ◽  
Mario Trigiante
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Boundary Conditions ◽  
Charged Black Hole ◽  
Dual Theory ◽  
Real Numbers ◽  
Hairy Black Holes ◽  
Interpolation Parameter ◽  
Black Hole Solutions ◽  
Extremal Black Holes

Abstract In this article we study a family of four-dimensional, $$ \mathcal{N} $$ N = 2 supergravity theories that interpolates between all the single dilaton truncations of the SO(8) gauged $$ \mathcal{N} $$ N = 8 supergravity. In this infinitely many theories characterized by two real numbers — the interpolation parameter and the dyonic “angle” of the gauging — we construct non-extremal electrically or magnetically charged black hole solutions and their supersymmetric limits. All the supersymmetric black holes have non-singular horizons with spherical, hyperbolic or planar topology. Some of these supersymmetric and non-extremal black holes are new examples in the $$ \mathcal{N} $$ N = 8 theory that do not belong to the STU model. We compute the asymptotic charges, thermodynamics and boundary conditions of these black holes and show that all of them, except one, introduce a triple trace deformation in the dual theory.

scholarly journals ENERGY EXTRACTION FROM GRAVITATIONAL COLLAPSE TO STATIC BLACK HOLES

2003 ◽  
Vol 12 (01) ◽  
pp. 121-127 ◽  
Author(s):  
REMO RUFFINI ◽  
LUCA VITAGLIANO
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Extraction Process ◽  
Maximum Efficiency ◽  
Energy Extraction ◽  
Mass Energy ◽  
Classical Level ◽  
Static Black Hole ◽  
Exact Analytic Expression ◽  
Analytic Expression

The mass-energy formula of black holes implies that up to 50% of the energy can be extracted from a static black hole. Such a result is reexamined using the recently established analytic formulas for the collapse of a shell and the expression for the irreducible mass of a static black hole. It is shown that the efficiency of energy extraction process during the formation of the black hole is linked in an essential way to the gravitational binding energy, the formation of the horizon and the reduction of the kinetic energy of implosion. Here a maximum efficiency of 50% in the extraction of the mass energy is shown to be generally attainable in the collapse of a spherically symmetric shell: surprisingly this result holds as well in the two limiting cases of the Schwarzschild and extreme Reissner–Nordström space–times. Moreover, the analytic expression recently found for the implosion of a spherical shell to an already formed black hole leads to a new exact analytic expression for the energy extraction which results in an efficiency strictly less than 100% for any physical implementable process. There appears to be no incompatibility between General Relativity and Thermodynamics at this classical level.

Chiral asymmetries in near-horizon region of charged black hole and teleparallelism

2021 ◽  
pp. 2150073
Author(s):  
L. C. Garcia de Andrade
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Magnetic Monopoles ◽  
Charged Black Hole ◽  
Kerr Spacetime ◽  
Charged Black Holes ◽  
Physical Information ◽  
Quantum Anomalies ◽  
Spacetime Metric

The issue of encoding physical information into metric structure of physical theories has been discussed recently by the author in the case of black hole teleparallelism. In this paper, one obtains a teleparallel chiral currents from quantum anomalies and topological torsional invariants of Nieh-Yan type. The Pontryagin index is also obtained in the case of rotating Kerr spacetime metric of non-static black holes. Magnetic monopoles which appears in this approach can be eliminated by a torsion constraint. These ideas are applied to Kerr and Kerr–Newmann charged black holes.

scholarly journals Magnetized Reissner–Nordström black hole restores cosmic censorship conjecture

2019 ◽  
Vol 49 ◽  
pp. 1960020 ◽  
Author(s):  
Sanjar Shaymatov
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Threshold Value ◽  
Cosmic Censorship ◽  
Black Hole Horizon ◽  
Charged Black Hole ◽  
The Magnetic Field ◽  
Cosmic Censorship Conjecture

We investigate the effect of magnetic field on the process of overcharging magnetized Reissner–Nordström black hole. It is well known that a four dimensional charged black hole could be overcharged. Contrary to this, we show that a magnetized charged black hole could not be overcharged beyond threshold value of the magnetic field. This occurs because the magnetic field does not allow for particle to reach black hole horizon. Thus magnetic field beyond its threshold value could restore the cosmic censorship conjecture.

scholarly journals Distributions of extremal black holes in Calabi-Yau compactifications

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
George Hulsey ◽  
Shamit Kachru ◽  
Sungyeon Yang ◽  
Max Zimet
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Moduli Space ◽  
Black Hole Horizon ◽  
Extremal Black Hole ◽  
Vector Multiplet ◽  
Horizon Area ◽  
Extremal Black Holes

Abstract We study non-supersymmetric extremal black hole excitations of 4d $$ \mathcal{N} $$ N = 2 supersymmetric string vacua arising from compactification on Calabi-Yau threefolds. The values of the (vector multiplet) moduli at the black hole horizon are governed by the attractor mechanism. This raises natural questions, such as “what is the distribution of attractor points on moduli space?” and “how many attractor black holes are there with horizon area up to a certain size?” We employ tools developed by Denef and Douglas [1] to answer these questions.

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