scholarly journals Distance between collapsing matter and apparent horizon in evaporating black holes

2021 ◽  
Vol 104 (6) ◽  
Author(s):  
Pei-Ming Ho ◽  
Yoshinori Matsuo ◽  
Yuki Yokokura
Keyword(s):  
Black Holes ◽  
Apparent Horizon

scholarly journals Gravitational dynamics in the toy model of the Higgs-dark matter sector: the field theoretic perspective

2020 ◽  
Vol 80 (11) ◽  
Author(s):  
Anna Nakonieczna ◽  
Łukasz Nakonieczny
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Mass Parameter ◽  
Apparent Horizon ◽  
Higgs Field ◽  
Radial Pressure ◽  
Model Parameters ◽  
Complex Scalar ◽  
Matter Sector ◽  
Scalar Gravity

AbstractThe objective of the paper was to examine gravitational evolutions in the Higgs-dark matter sector toy model. The real part of the Higgs doublet was modelled by a neutral scalar. Two dark matter candidates introduced were the dark photon and a charged complex scalar. Non-minimal couplings of both scalars to gravity were included. The coupling channels between the ordinary and dark matter sectors were kinetic mixing between the electromagnetic and dark U(1) fields and the Higgs portal coupling among the scalars. The structures of emerging singular spacetimes were either of Schwarzschild or Reissner–Nordström types. The non-minimal scalar–gravity couplings led to an appearance of timelike portions of apparent horizons where they transform from spacelike to null. The features of dynamical black holes were described as functions of the model parameters. The black holes formed later and their radii and masses were smaller as the mass parameter of the complex scalar increased. The dependencies on the coupling of the Higgs field to gravity exhibited extrema, which were a maximum for the time of the black holes formation and minima in the cases of their radii and masses. A set of quantities associated with an observer moving with the evolving matter was proposed. The energy density, radial pressure and pressure anisotropy within dynamical spacetimes get bigger as the singularity is approached. The increase is more considerable in the Reissner–Nordström spacetimes. The apparent horizon local temperature changes monotonically in the minimally coupled case and non-monotonically when non-minimal scalar–gravity couplings are involved.

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 Thermodynamic structure of field equations near apparent horizon for radiating black holes

2014 ◽  
Vol 29 (34) ◽  
pp. 1450188 ◽  
Author(s):  
Uma Papnoi ◽  
Megan Govender ◽  
Sushant G. Ghosh
Keyword(s):  
Black Holes ◽  
Apparent Horizon ◽  
Higher Dimensions ◽  
Spherically Symmetric ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Four Dimensions ◽  
Thermodynamic Structure ◽  
Kinematical Parameters

We study the intriguing analogy between gravitational dynamics of the horizon and thermodynamics for the case of nonstationary radiating spherically symmetric black holes both in four dimensions and higher dimensions. By defining all kinematical parameters of nonstationary radiating black holes in terms of null vectors, we demonstrate that it is possible to interpret the Einstein field equations near the apparent horizon in the form of a thermodynamical identity T dS = dE+P dV.

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 Generalized entropies and corresponding holographic dark energy models

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
H. Moradpour ◽  
A. H. Ziaie ◽  
M. Kord Zangeneh
Keyword(s):  
Black Holes ◽  
Dark Energy ◽  
Holographic Dark Energy ◽  
Apparent Horizon ◽  
Tsallis Entropy ◽  
Accelerating Universe ◽  
Frw Universe ◽  
Energy Models ◽  
Generalized Entropies ◽  
The Universe

Abstract Using Tsallis statistics and its relation with Boltzmann entropy, the Tsallis entropy content of black holes is achieved, a result in full agreement with a recent study (Mejrhit and Ennadifi in Phys Lett B 794:24, 2019). In addition, employing Kaniadakis statistics and its relation with that of Tsallis, the Kaniadakis entropy of black holes is obtained. The Sharma-Mittal and Rényi entropy contents of black holes are also addressed by employing their relations with Tsallis entropy. Thereinafter, relying on the holographic dark energy hypothesis and the obtained entropies, two new holographic dark energy models are introduced and their implications on the dynamics of a flat FRW universe are studied when there is also a pressureless fluid in background. In our setup, the apparent horizon is considered as the IR cutoff, and there is not any mutual interaction between the cosmic fluids. The results indicate that the obtained cosmological models have (i) notable powers to describe the cosmic evolution from the matter-dominated era to the current accelerating universe, and (ii) suitable predictions for the universe age.

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 Formation of dynamically transversely trapping surfaces and the stretched hoop conjecture

2020 ◽  
Vol 2020 (5) ◽  
Author(s):  
Hirotaka Yoshino ◽  
Keisuke Izumi ◽  
Tetsuya Shiromizu ◽  
Yoshimune Tomikawa
Keyword(s):  
Black Holes ◽  
Initial Data ◽  
Apparent Horizon ◽  
Ring System ◽  
Conformally Flat ◽  
Trapped Surfaces ◽  
Marginally Trapped Surface ◽  
Spherical Topology ◽  
Hoop Conjecture ◽  
Trapped Surface

Abstract A dynamically transversely trapping surface (DTTS) is a new concept for an extension of a photon sphere that appropriately represents a strong gravity region and has close analogy with a trapped surface. We study formation of a marginally DTTS in time-symmetric, conformally flat initial data with two black holes, with a spindle-shaped source, and with a ring-shaped source, and clarify that $\mathcal{C}\lesssim 6\pi GM$ describes the condition for the DTTS formation well, where $\mathcal{C}$ is the circumference and $M$ is the mass of the system. This indicates that an understanding analogous to the hoop conjecture for the horizon formation is possible. Exploring the ring system further, we find configurations where a marginally DTTS with the torus topology forms inside a marginally DTTS with the spherical topology, without being hidden by an apparent horizon. There also exist configurations where a marginally trapped surface with the torus topology forms inside a marginally trapped surface with the spherical topology, showing a further similarity between DTTSs and trapped surfaces.

scholarly journals Thermodynamics of a Non-Stationary Black Hole Based on Generalized Uncertainty Principle

2017 ◽  
Vol 1 (2) ◽  
pp. 127
Author(s):  
Mustari Mustari ◽  
Yuant Tiandho
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Uncertainty Principle ◽  
Correction Term ◽  
Apparent Horizon ◽  
Generalized Uncertainty Principle ◽  
Minimum Length ◽  
Theory Of Relativity ◽  
Stationary Black Hole ◽  
Gravitational Fields

In the general theory of relativity (GTR), black holes are defined as objects with very strong gravitational fields even light can not escape. Therefore, according to GTR black hole can be viewed as a non-thermodynamic object. The worldview of a black hole began to change since Hawking involves quantum field theory to study black holes and found that black holes have temperatures that analogous to black body radiation. In the theory of quantum gravity there is a term of the minimum length of an object known as the Planck length that demands a revision of Heisenberg's uncertainty principle into a Generalized Uncertainty Principle (GUP). Based on the relationship between the momentum uncertainty and the characteristic energy of the photons emitted by a black hole, the temperature and entropy of the non-stationary black hole (Vaidya-Bonner black hole) were calculated. The non-stationary black hole was chosen because it more realistic than static black holes to describe radiation phenomena. Because the black hole is dynamic then thermodynamics studies are conducted on both black hole horizons: the apparent horizon and its event horizon. The results showed that the dominant correction term of the temperature and entropy of the Vaidya-Bonner black hole are logarithmic.

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