scholarly journals The interior volume calculation for an axially symmetric black hole

2019 ◽  
Vol 788 ◽  
pp. 464-467 ◽  
Author(s):  
Xin-Yang Wang ◽  
Wen-Biao Liu
Keyword(s):  
Black Hole ◽  
Axially Symmetric ◽  
Volume Calculation ◽  
Symmetric Black Hole ◽  
Interior Volume

scholarly journals High-energy collision of particles in the magnetic field far from black holes

2014 ◽  
Vol 29 (29) ◽  
pp. 1450151
Author(s):  
O. B. Zaslavskii
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Center Of Mass ◽  
High Energy ◽  
Axially Symmetric ◽  
High Energy Collision ◽  
Mass Frame ◽  
Symmetric Black Hole ◽  
Rotating Star ◽  
The Magnetic Field

We consider collision of two particles in the axially symmetric black hole metric in the magnetic field. If the value of the angular momentum |L| of one particles grows unbound (but its Killing energy remains fixed) one can achieve unbound energy in the center-of-mass frame E c.m. In the absence of the magnetic field, collision of this kind is known to happen in the ergoregion. However, if the magnetic field strength B is also large, with the ratio |L|/B being finite, large E c.m. can be achieved even far from a black hole, in the almost flat region. Such an effect also occurs in the metric of a rotating star.

scholarly journals Two mass conjectures on axially symmetric black hole-disk systems

2019 ◽  
Vol 99 (2) ◽  
Author(s):  
Wojciech Kulczycki ◽  
Patryk Mach ◽  
Edward Malec
Keyword(s):  
Black Hole ◽  
Axially Symmetric ◽  
Symmetric Black Hole

scholarly journals Blandford-Znajek mechanism in the general stationary axially-symmetric black-hole spacetime

2021 ◽  
Vol 2021 (12) ◽  
pp. 002
Author(s):  
R.A. Konoplya ◽  
J. Kunz ◽  
A. Zhidenko
Keyword(s):  
Black Hole ◽  
Deformation Parameter ◽  
Rotation Parameter ◽  
Energy Extraction ◽  
Axially Symmetric ◽  
Asymptotically Flat ◽  
Kerr Spacetime ◽  
Black Hole Spacetime ◽  
Symmetric Black Hole ◽  
The Magnetic Field

Abstract We consider the Blandford-Znajek process of electromagnetic extraction of energy from a general axially symmetric asymptotically flat slowly rotating black hole. Using the general parametrization of the black-hole spacetime we construct formulas for the flux of the magnetic field and the rate of energy extraction, which are valid not only for the Kerr spacetime, but also for its arbitrary axially symmetric deformations. We show that in the dominant order these quantities depend only on a single deformation parameter, which relates the spin frequency of a black hole with its rotation parameter.

scholarly journals Bumblebee gravity with a Kerr–Sen like solution and its Shadow

2021 ◽  
Vol 81 (4) ◽  
Author(s):  
Sohan Kumar Jha ◽  
Anisur Rahaman
Keyword(s):  
Black Hole ◽  
Emission Rate ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Field Vector ◽  
Axially Symmetric ◽  
System A ◽  
Black Hole Spacetime ◽  
Symmetric Black Hole ◽  
Careful Investigation

AbstractWe have considered the bumblebee gravity model where lorentz-violating (LV) scenario gets involved through a bumblebee field vector field $$B_\mu $$ B μ . A spontaneous symmetry breaking allows the field to acquires a vacuum expectation value that generates LV into the system. A Kerr–Sen-like solution has been found out starting from the generalized form of a radiating stationery axially symmetric black hole metric. We compute the effective potential offered by the null geodesics in the bumblebee rotating black hole spacetime. The shadow has been sketched for different variations of the parameters involved in the system. A careful investigation has been carried out to study how the shadow gets affected when Lorentz violation enters into the picture. The emission rate of radiation has also been studied and how it varies with the LV parameter $$\ell $$ ℓ is studied scrupulously.

scholarly journals Can shadows reflect phase structures of black holes?

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Ming Zhang ◽  
Minyong Guo
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Phase Structure ◽  
Black Hole Thermodynamics ◽  
Spherically Symmetric ◽  
Axially Symmetric ◽  
Phase Structures ◽  
Correct Information ◽  
Symmetric Black Hole

Abstract The relation between the black hole shadow and the black hole thermodynamics is investigated. We find that the phase structure can be reflected by the shadow radius for the spherically symmetric black hole. We also find that the shadow size gives correct information but the distortion of the shadow gives wrong information of the phase structure for the axially symmetric black hole.

Entropy in a d-dimensional charged black hole

2018 ◽  
Vol 33 (27) ◽  
pp. 1850159 ◽  
Author(s):  
Shad Ali ◽  
Xin-Yang Wang ◽  
Wen-Biao Liu
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Hawking Radiation ◽  
Space Time ◽  
Charged Black Hole ◽  
Schwarzschild Black Hole ◽  
Proportionality Coefficient ◽  
Proportional Relation ◽  
Hamiltonian Analysis ◽  
Interior Volume

Christodoulou and Rovelli have shown that the interior volume of a Schwarzschild black hole grows linearly with time. The entropy of a scalar field in this interior volume of a Schwarzschild black hole has been calculated and shown to increase linearly with the advanced time too. In this paper, considering Hawking radiation from a d-dimensional charged black hole, we investigate the proportional relation between the entropy of the scalar field in the interior volume and the Bekenstein–Hawking entropy using the method of our previous work. We also derive this proportionality relation using Hamiltonian analysis and find a consistent result. We then investigate the proportionality coefficient with respect to d and find that it gradually decreases as the dimension of space–time increases.

The entropy evolution of a noncommutative black hole under Hawking radiation

2020 ◽  
Vol 35 (30) ◽  
pp. 2050194
Author(s):  
Peng Wen ◽  
Xin-Yang Wang ◽  
Wen-Biao Liu
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Scalar Field ◽  
Hawking Radiation ◽  
New Physics ◽  
Evaporation Process ◽  
Final State ◽  
Loss Of Information ◽  
Proportion Function ◽  
Interior Volume

By calculating the entropy of a scalar field in the interior volume of noncommutative black holes and considering an infinitesimal process of Hawking radiation, a proportion function is constructed that reflects the evolution relation between the scalar field entropy and Bekenstein–Hawking entropy under Hawking radiation. Comparing with the case of Schwarzschild black holes, the new physics of this research can be expanded to the later stage of Hawking radiation. From the result, we find that the proportion function is still a constant in the earlier stage of Hawking radiation, which is identical to the case of Schwarzschild black holes. As Hawking radiation goes into the later stage, the behavior of the function will be dominated by the noncommutative effect. In this circumstance, the proportion function is no longer a constant and decreases with the evaporation process. When the noncommutative black hole evolves into its final state with Hawking radiation, the interior volume will converge to a certain value, which implies that the loss of information of the black hole during the evaporation process will finally be stored in the limited interior volume.

scholarly journals Horizon Thermodynamics in D-Dimensional f(R) Black Hole

Entropy ◽  
2020 ◽  
Vol 22 (11) ◽  
pp. 1246
Author(s):  
Chenrui Zhu ◽  
Rong-Jia Yang
Keyword(s):  
Black Hole ◽  
Spherically Symmetric ◽  
Higher Dimensional ◽  
Horizon Thermodynamics ◽  
Symmetric Black Hole

We consider whether the new horizon-first law works in higher-dimensional f(R) theory. We firstly obtain the general formulas to calculate the entropy and the energy of a general spherically-symmetric black hole in D-dimensional f(R) theory. For applications, we compute the entropies and the energies of some black hokes in some interesting higher-dimensional f(R) theories.

The entropy evolution of a Schwarzschild–(Anti) de Sitter black hole

2020 ◽  
Vol 29 (07) ◽  
pp. 2050048
Author(s):  
Xin-Yang Wang ◽  
Yi-Ru Wang ◽  
Wen-Biao Liu
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Scalar Field ◽  
Hawking Radiation ◽  
Dynamical Variable ◽  
De Sitter ◽  
The One ◽  
Definition Of ◽  
Spherically Symmetry ◽  
Interior Volume

Based on the definition of the interior volume of spherically symmetry black holes, the interior volume of Schwarzschild–(Anti) de Sitter black holes is calculated. It is shown that with the cosmological constant ([Formula: see text]) increasing, the changing behaviors of both the position of the largest hypersurface and the interior volume for the Schwarzschild–Anti de Sitter black hole are the same as the Schwarzschild–de Sitter black hole. Considering a scalar field in the interior volume and Hawking radiation with only energy, the evolution relation between the scalar field entropy and Bekenstein–Hawking entropy is constructed. The results show that the scalar field entropy is approximately proportional to Bekenstein–Hawking entropy during Hawking radiation. Meanwhile, the proportionality coefficient is also regarded as a constant approximately with the increasing [Formula: see text]. Furthermore, considering [Formula: see text] as a dynamical variable, the modified Stefan–Boltzmann law is proposed which can be used to describe the variation of both the mass and [Formula: see text] under Hawking radiation. Using this modified law, the evolution relation between the two types of entropy is also constructed. The results show that the coefficient for Schwarzschild–de Sitter black holes is closer to a constant than the one for Schwarzschild–Anti de Sitter black holes during the evaporation process. Moreover, we find that for Hawking radiation carrying only energy, the evolution relation is a special case compared with the situation that the mass and [Formula: see text] are both considered as dynamical variables.

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