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.

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 BRANE WORLD IN A TOPOLOGICAL BLACK HOLES IN ASYMPTOTICALLY FLAT SPACE–TIME

2001 ◽  
Vol 16 (26) ◽  
pp. 1703-1710 ◽  
Author(s):  
DONAM YOUM
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Scalar Field ◽  
Flat Space ◽  
Space Time ◽  
Brane World ◽  
Black Hole Horizon ◽  
World Model ◽  
Asymptotically Flat ◽  
Bulk Scalar Field

We study static brane configurations in the bulk background of the topological black holes in asymptotically flat space–time and find that such configurations are possible even for flat black hole horizon, unlike the AdS black hole case. We construct the brane world model with an orbifold structure S1/Z2 in such bulk background and study massless bulk scalar field.

scholarly journals Black hole hair removal for N = 4 CHL models

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Subhroneel Chakrabarti ◽  
Suresh Govindarajan ◽  
P. Shanmugapriya ◽  
Yogesh K. Srivastava ◽  
Amitabh Virmani
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Degrees Of Freedom ◽  
Microscopic Analysis ◽  
Flat Space ◽  
Special Care ◽  
Hair Removal ◽  
Partition Functions ◽  
Rotating Black Holes

Abstract Although BMPV black holes in flat space and in Taub-NUT space have identical near-horizon geometries, they have different indices from the microscopic analysis. For K3 compactification of type IIB theory, Sen et al. in a series of papers identified that the key to resolving this puzzle is the black hole hair modes: smooth, normalisable, bosonic and fermionic degrees of freedom living outside the horizon. In this paper, we extend their study to N = 4 CHL orbifold models. For these models, the puzzle is more challenging due to the presence of the twisted sectors. We identify hair modes in the untwisted as well as twisted sectors. We show that after removing the contributions of the hair modes from the microscopic partition functions, the 4d and 5d horizon partition functions agree. Special care is taken to present details on the smoothness analysis of hair modes for rotating black holes, thereby filling an essential gap in the literature.

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.

Super-Penrose process

2020 ◽  
Vol 35 (02n03) ◽  
pp. 2040058
Author(s):  
O. B. Zaslavskii
Keyword(s):  
Black Hole ◽  
Flat Space ◽  
Space Time ◽  
Centre Of Mass ◽  
Rotating Black Hole ◽  
Mass Frame ◽  
Penrose Process ◽  
Energy Formula ◽  
Full Classification

If two particles collide near a rotating black hole, their energy in the centre of mass frame can become unbounded under certain conditions. In doing so, the Killing energy [Formula: see text] of debris at infinity is, in general, remain restricted. If [Formula: see text] is also unbounded, this is called the super-Penrose process. We elucidate when such a process is possible and give full classification of corresponding relativistic objects for rotating space-times. We also discuss the case of a pure electric super-Penrose process that is valid even in the flat space-time. The key role in consideration is played by the Wald inequalities.

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.

scholarly journals The Thermodynamic Relationship between the RN-AdS Black Holes and the RN Black Hole in Canonical Ensemble

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Yu-Bo Ma ◽  
Li-Chun Zhang ◽  
Jian Liu ◽  
Ren Zhao ◽  
Shuo Cao
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Flat Space ◽  
Space Time ◽  
Asymptotically Flat ◽  
Time Space ◽  
Ads Black Holes ◽  
Different Types ◽  
Thermodynamic Relationship ◽  
The Relationship

In this paper, by analyzing the thermodynamic properties of charged AdS black hole and asymptotically flat space-time charged black hole in the vicinity of the critical point, we establish the correspondence between the thermodynamic parameters of asymptotically flat space-time and nonasymptotically flat space-time, based on the equality of black hole horizon area in the two different types of space-time. The relationship between the cavity radius (which is introduced in the study of asymptotically flat space-time charged black holes) and the cosmological constant (which is introduced in the study of nonasymptotically flat space-time) is determined. The establishment of the correspondence between the thermodynamics parameters in two different types of space-time is beneficial to the mutual promotion of different time-space black hole research, which is helpful to understand the thermodynamics and quantum properties of black hole in space-time.

scholarly journals Magnetized Particle Motion around Black Holes in Conformal Gravity: Can Magnetic Interaction Mimic Spin of Black Holes?

Universe ◽  
2020 ◽  
Vol 6 (3) ◽  
pp. 44 ◽  
Author(s):  
Kamoliddin Haydarov ◽  
Ahmadjon Abdujabbarov ◽  
Javlon Rayimbaev ◽  
Bobomurat Ahmedov
Keyword(s):  
Magnetic Field ◽  
Black Holes ◽  
Black Hole ◽  
Particle Motion ◽  
Center Of Mass ◽  
Conformal Gravity ◽  
Mass Energy ◽  
Particle Collisions ◽  
Center Of Mass Energy ◽  
Sgr A

Magnetized particle motion around black holes in conformal gravity immersed in asymptotically uniform magnetic field has been studied. We have also analyzed the behavior of magnetic fields near the horizon of the black hole in conformal gravity and shown that with the increase of conformal parameters L and N the value of angular component of magnetic field at the stellar surface decreases. The maximum value of the effective potential corresponding to circular motion of the magnetized particle increases with the increase of conformal parameters. It is shown that in all cases of neutral, charged and magnetized particle collisions in the black hole environment the center-of-mass energy decreases with the increase of conformal parameters L and N. In the case of the magnetized and negatively charged particle collisions, the innermost collision point with the maximum center-of-mass energy comes closer to the central object due to the effects of the parameters of the conformal gravity. We have applied the results to the real astrophysical scenario when a pulsar treated as a magnetized particle is orbiting the super massive black hole (SMBH) Sgr A* in the center of our galaxy in order to obtain the estimation of magnetized compact object’s orbital parameter. The possible detection of pulsar in Sgr A* close environment can provide constraints on black hole parameters. Here we have shown that there is degeneracy between spin of SMBH and ambient magnetic field and consequently the interaction of magnetic field ∼ 10 2 Gauss with magnetic moment of magnetized neutron star can in principle mimic spin of Kerr black holes up to 0.6 .

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