scholarly journals Remarks on non-singular black holes

2018 ◽  
Vol 168 ◽  
pp. 01001 ◽  
Author(s):  
Valeri P. Frolov
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Apparent Horizon ◽  
External Observer ◽  
Quantum Radiation ◽  
Black Hole Background ◽  
Black Hole Interior ◽  
Mass Inflation ◽  
The Given ◽  
Self Consistency

We briefly discuss non-singular black hole models, with the main focus on the properties of non-singular evaporating black holes. Such black holes possess an apparent horizon, however the event horizon may be absent. In such a case, the information from the black hole interior may reach the external observer after the complete evaporation of the black hole. This model might be used for the resolution of the information loss puzzle. However, as we demonstrate, in a general case the quantum radiation emitted from the black hole interior, calculated in the given black hole background, is very large. This outburst of the radiation is exponentially large for models with the redshift function α = 1. We show that it can be suppressed by including a non-trivial redshift function. However, even this suppression is not enough to guarantee self-consistency of the model. This problem is a manifestation of a general problem, known as the "mass inflation". We briefly comment on possible ways to overcome this problem in the models of non-singular evaporating black holes.

Frontiers of Quantum Black Holes

2020 ◽  
Vol 29 (11) ◽  
pp. 10-16
Author(s):  
Wontae KIM ◽  
Mu-In PARK
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Direct Detection ◽  
Occupation Number ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Quantum Radiation ◽  
Points Of View ◽  
Massless Quantum

A black hole is a theoretical prediction of Einstein’s general theory of relativity, differently from Newtonian gravity, which is a non-relativistic gravity. In recent few years, its direct detection via gravitational waves and other multi-messenger observations have made it possible to test the prediction and hence its associated general relativity. From purely theoretical points of view, general relativity cannot be a complete description due to its not being compatible with quantum mechanics, which is a successful description of microscopic objects. In this article, we introduce the conceptional development of quantum-gravity theories and give brief sketches of fundamental problems in quantum black holes. As an interesting model of quantum black holes, we consider a collapsing shell of matter to form a Hayward black hole and investigate semiclassically quantum radiation from the shell. By using the Israel’s formulation and the functional Schrödinger formulation for massless quantum radiation, we find that the Hawking temperature can be deduced from the occupation number of excited states when the shell approaches its own horizon.

scholarly journals Can a false vacuum bubble remove the singularity inside a black hole?

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Suddhasattwa Brahma ◽  
Dong-han Yeom
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Thin Shell ◽  
Apparent Horizon ◽  
False Vacuum ◽  
De Sitter ◽  
Singularity Formation ◽  
Null Direction ◽  
Singularity Resolution ◽  
Hole Model

Abstract We investigate a regular black hole model with a de Sitter-like core at its center. This type of a black hole model with a false vacuum core was introduced with the hope of singularity-resolution and is a common feature shared by many regular black holes. In this paper, we examine this claim of a singularity-free black hole by employing the thin-shell formalism, and exploring its dynamics, within the Vaidya approximation. We find that during gravitational collapse, the shell necessarily moves along a space-like direction. More interestingly, during the evaporation phase, the shell and the outer apparent horizon approach each other but, unless the evaporation takes place very rapidly, the approaching tendency is too slow to avoid singularity-formation. This shows that albeit a false vacuum core may remove the singularity along the ingoing null direction, there still exists a singularity along the outgoing null direction, unless the evaporation is very strong.

scholarly journals Evaporation of black hole under the effect of quantum gravity

2021 ◽  
Author(s):  
Riasat Ali ◽  
Rimsha Babar ◽  
Muhammad Asgher ◽  
Syed Asif Ali Shah
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Quantum Gravity ◽  
Generalized Uncertainty Principle ◽  
Hawking Temperature ◽  
Charged Black Hole ◽  
Global Monopole ◽  
De Sitter ◽  
Quantum Radiation ◽  
Charged Boson

This paper provides an extension for Hawking temperature of Reissner–Nordström-de Sitter (RN-DS) black hole (BH) with global monopole as well as [Formula: see text]D charged black hole. We consider the black holes metric and investigate the effects of quantum gravity ([Formula: see text]) on Hawking radiation. We investigate the charged boson particles tunneling through the horizon of black holes by using the Hamilton–Jacobi ansatz phenomenon. In our investigation, we study the quantum radiation to analyze the Lagrangian wave equation with generalized uncertainty principle and calculate the modified Hawking temperatures for black holes. Furthermore, we analyze the charge and correction parameter effects on the modified Hawking temperature and examine the stable and unstable condition of RN-DS BH with global monopole as well as [Formula: see text]D charged black hole.

scholarly journals BLACK HOLES IN THEORIES WITH LARGE EXTRA DIMENSIONS: A REVIEW

2004 ◽  
Vol 19 (29) ◽  
pp. 4899-4951 ◽  
Author(s):  
PANAGIOTA KANTI
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Hawking Radiation ◽  
Extra Dimensions ◽  
Large Extra Dimensions ◽  
Life Time ◽  
High Energy ◽  
High Energy Particle ◽  
Radiation Spectra ◽  
Black Hole Background

We start by reviewing the existing literature on the creation of black holes during high-energy particle collisions, both in the absence and in the presence of extra, compact, spacelike dimensions. Then, we discuss in detail the properties of the produced higher-dimensional black holes, namely the horizon radius, temperature and life-time, as well as the physics that governs the evaporation of these objects, through the emission of Hawking radiation. We first study the emission of visible Hawking radiation on the brane: we derive a master equation for the propagation of fields with arbitrary spin in the induced-on-the-brane black hole background, and we review all existing results in the literature for the emission of scalars, fermions and gauge bosons during the spin-down and Schwarzschild phases of the life of the black hole. Both analytical and numerical results for the graybody factors and radiation spectra are reviewed and exact results for the number and type of fields emitted on the brane as a function of the dimensionality of space–time are discussed. We finally study the emission of Hawking radiation in the bulk: graybody factors and radiation spectra are presented for the emission of scalar modes, and the ratio of the missing energy over the visible one is calculated for different values of the number of extra dimensions.

Thermodynamics from field equations for charged radiating rotating black hole near horizon

2020 ◽  
Vol 35 (19) ◽  
pp. 2050092
Author(s):  
Uma Papnoi ◽  
Sushant G. Ghosh
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Field Equation ◽  
Thermodynamic Parameters ◽  
Apparent Horizon ◽  
Einstein Field Equation ◽  
Axially Symmetric ◽  
Field Equations ◽  
Rotating Black Hole

It is well known that near horizon black hole space–times show a resemblance to thermodynamic systems, it is easy to associate the thermodynamic parameters like temperature and entropy with them. In this paper, we study the connection between gravitational dynamics of the horizon and thermodynamics for the case of charged radiating rotating axially symmetric black holes. It is shown that Einstein field equation near apparent horizon can be interpreted in the form of thermodynamic law, i.e. [Formula: see text].

scholarly journals BLACK HOLES RADIATE BUT DO NOT EVAPORATE

2005 ◽  
Vol 14 (12) ◽  
pp. 2257-2261 ◽  
Author(s):  
HRVOJE NIKOLIĆ
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Hawking Radiation ◽  
Negative Energy ◽  
Black Hole Mass ◽  
Black Hole Radiation ◽  
Semiclassical Gravity ◽  
Black Hole Interior ◽  
Semiclassical State ◽  
Infinite Temperature

During the black hole radiation, the interior contains all the matter of the initial black hole, together with the negative energy quanta entangled with the exterior Hawking radiation. Neither the initial matter nor the negative energy quanta evaporate from the black hole interior. Therefore, the information is not lost during the radiation. The black hole mass eventually drops to zero in semiclassical gravity, but this semiclassical state has an infinite temperature and still contains all the initial matter together with the negative energy entangled with the exterior radiation.

ON THE WHEELER-DEWITT EQUATION FOR BLACK HOLES

1994 ◽  
Vol 03 (03) ◽  
pp. 579-591 ◽  
Author(s):  
M.D. POLLOCK
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Schrödinger Equation ◽  
Schrodinger Equation ◽  
Apparent Horizon ◽  
Hamiltonian Formalism ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Two Dimensional ◽  
Superstring Theory

Integration over the angular coordinates of the evaporating, four-dimensional Schwarzschild black hole leads to a two-dimensional action, for which the Wheeler-DeWitt equation has been found by Tomimatsu, on the apparent horizon, where the Vaidya metric is valid, using the Hamiltonian formalism of Hajicek. For the Einstein theory of gravity coupled to a massless scalar field ζ, the wave function Ψ obeys the Schrödinger equation [Formula: see text], where M is the mass of the hole. The solution is [Formula: see text], where k2 is the separation constant, and for k2>0 the hole evaporates at the rate Ṁ=−k2/4M2, in agreement with the result of Hawking. Here, this analysis is generalized to the two-dimensional theory [Formula: see text], which subsumes the spherical black holes formulated in D≥4 dimensions, when A = ½ (D - 2) (D - 3)ϕ2 (D - 4)/(D - 2), B=2(D−3)/(D−2), C=1, and also the twodimensional black hole identified by Witten and by Gautam et al., when A=4/α′, B=2, C=1/8π, c=+8/α′ being (minus) the central charge. In all cases an analogous Schrödinger equation is obtained. The evaporation rate is [Formula: see text] when D≥4 and [Formula: see text] when D=2. Since Ψ evolves without violation of unitarity, there is no loss of information during the evaporation process, in accord with the principle of black-hole complementarity introduced by Susskind et al. Finally, comparison with the four-dimensional, cosmological Schrödinger equation, obtained by reduction of the ten-dimensional heterotic superstring theory including terms [Formula: see text], shows in both cases that there is a positive semi-definite potential which evolves to zero, this corresponding to the ground state, which is Minkowski space.

scholarly journals STRING THEORY ON THREE-DIMENSIONAL BLACK HOLES

1998 ◽  
Vol 13 (08) ◽  
pp. 1229-1262 ◽  
Author(s):  
MAKOTO NATSUUME ◽  
YUJI SATOH
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
String Theory ◽  
Three Dimensional ◽  
Matching Condition ◽  
Target Space ◽  
Black Hole Mass ◽  
Curved Space ◽  
Conformal Field ◽  
Black Hole Background

We investigate the string theory on three-dimensional black holes discovered by Bañados, Teitelboim and Zanelli in the framework of conformal field theory. The model is described by an orbifold of the [Formula: see text] WZW model. The spectrum is analyzed by solving the level matching condition and we obtain winding modes. We then study the ghost problem and show explicit examples of physical states with negative norms. We discuss the tachyon propagation and the target space geometry, which are irrelevant to the details of the spectrum. we find a self-dual T-duality transformation reversing the black hole mass. We also discuss difficulties in string theory on curved space–time and possibilities of obtaining a sensible string theory on three-dimensional black holes. This work is the first attempt to quantize a string theory in a black hole background with an infinite number of propagating modes.

scholarly journals WAVE PROPAGATION IN STRINGY BLACK HOLE

1993 ◽  
Vol 08 (18) ◽  
pp. 1701-1718 ◽  
Author(s):  
AVINASH DHAR ◽  
GAUTAM MANDAL ◽  
SPENTA R. WADIA
Keyword(s):  
Differential Equation ◽  
Black Holes ◽  
Black Hole ◽  
Wave Propagation ◽  
Two Dimensional ◽  
Tachyon Field ◽  
Oscillator Potential ◽  
Harmonic Oscillator Potential ◽  
Black Hole Background ◽  
The Right

We further study the non-perturbative formulation of two-dimensional black holes. We find a nonlinear differential equation satisfied by the tachyon in the black hole background. We show that singularities in the tachyon field configurations are always associated with divergent semiclassical expansions and are absent in the exact theory. We also discuss how the Euclidean black hole emerges from an analytically continued fermion theory that corresponds to the right side up harmonic oscillator potential.

scholarly journals Truly two-dimensional black holes under dimensional transitions of spacetime

2021 ◽  
Author(s):  
Wanpeng Tan
Keyword(s):  
Phase Transition ◽  
Black Holes ◽  
Black Hole ◽  
Degrees Of Freedom ◽  
Massive Star ◽  
Majorana Fermions ◽  
Two Dimensional ◽  
Gauge Bosons ◽  
The Core ◽  
Black Hole Interior

A sufficiently massive star in the end of its life will inevitably collapse into a black hole as more deconfined degrees of freedom make the core ever softer. One possible way to avoid the singularity in the end is by dimensional phase transition of spacetime. Indeed, the black hole interior, two-dimensional in nature, can be described well as a perfect fluid of free massless Majorana fermions and gauge bosons under a 2-d supersymmetric mirror model with new understanding of emergent gravity from dimensional evolution of spacetime. In particular, the 2-d conformal invariance of the black hole gives rise to desired consistent results for the interior microphysics and structures including its temperature, density, and entropy.

Sign in / Sign up

Export Citation Format

Share Document