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 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 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.

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.

scholarly journals Cosmic No-Hair in Spherically Symmetric Black Hole Spacetimes

2019 ◽  
Vol 20 (9) ◽  
pp. 3059-3090 ◽  
Author(s):  
João L. Costa ◽  
José Natário ◽  
Pedro Oliveira
Keyword(s):  
Black Hole ◽  
Spherically Symmetric ◽  
Black Hole Spacetimes ◽  
Symmetric Black Hole

Universality of spectra of black holes

2014 ◽  
Vol 29 (36) ◽  
pp. 1450191 ◽  
Author(s):  
Xiao-Xiong Zeng ◽  
Qiang Li ◽  
Yi-Wen Han
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Area Spectrum ◽  
Spherically Symmetric ◽  
Action Variable ◽  
Intrinsic Properties ◽  
Entropy Spectrum ◽  
Symmetric Black Hole

Using exclusively an action variable, we quantize a static, spherically symmetric black hole. The spacings of the quantized entropy spectrum and area spectrum are found to be equal to the values given by Bekenstein. Interestingly, we find the spectra are independent of the hairs of the black holes and the mode of motion of a particle outside the spacetime, which depends only on the intrinsic properties of the gravity. Our result shows that the spectra are universal provided the spacetime owns a horizon.

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