scholarly journals Equations of motion in general relativity of a small charged black hole

2008 ◽  
Vol 78 (10) ◽  
Author(s):  
T. Futamase ◽  
P. A. Hogan ◽  
Y. Itoh
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Equations Of Motion ◽  
Charged Black Hole

Disappearance of Black Hole Criticality in Semiclassical General Relativity

1997 ◽  
Vol 12 (10) ◽  
pp. 709-718 ◽  
Author(s):  
Takeshi Chiba ◽  
Masaru Siino
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Scalar Field ◽  
Critical Phenomena ◽  
Equations Of Motion ◽  
Quantum Effects ◽  
Hole Formation ◽  
Trace Anomaly ◽  
Self Similar ◽  
Similar Solutions

We investigate the quantum effects on the so-called critical phenomena in black hole formation. Quantum effects of a scalar field are treated semiclassically via a trace anomaly method. It is found that the demand of regularity at the origin implies the disappearance of the echo. It is also found that semiclassical equations of motion do not admit continuously self-similar solutions. The quantum effects would change the critical solution from a discretely self-similar one to a solution without critical phenomena.

scholarly journals Black holes in active galactic nuclei

2009 ◽  
Vol 5 (S261) ◽  
pp. 260-268
Author(s):  
M. J. Valtonen ◽  
S. Mikkola ◽  
D. Merritt ◽  
A. Gopakumar ◽  
H. J. Lehto ◽  
...  
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Strong Field ◽  
Equations Of Motion ◽  
Binary Black Holes ◽  
Time Dynamic ◽  
Black Hole Spacetime ◽  
First Time ◽  
Black Hole Masses

AbstractSupermassive black holes are common in centers of galaxies. Among the active galaxies, quasars are the most extreme, and their black hole masses range as high as to 6⋅1010M⊙. Binary black holes are of special interest but so far OJ287 is the only confirmed case with known orbital elements. In OJ287, the binary nature is confirmed by periodic radiation pulses. The period is twelve years with two pulses per period. The last four pulses have been correctly predicted with the accuracy of few weeks, the latest in 2007 with the accuracy of one day. This accuracy is high enough that one may test the higher order terms in the Post Newtonian approximation to General Relativity. The precession rate per period is 39°.1 ± 0°.1, by far the largest rate in any known binary, and the (1.83 ± 0.01)⋅1010M⊙primary is among the dozen biggest black holes known. We will discuss the various Post Newtonian terms and their effect on the orbit solution. The over 100 year data base of optical variations in OJ287 puts limits on these terms and thus tests the ability of Einstein's General Relativity to describe, for the first time, dynamic binary black hole spacetime in the strong field regime. The quadrupole-moment contributions to the equations of motion allows us to constrain the ‘no-hair’ parameter to be 1.0 ± 0.3 which supports the black hole no-hair theorem within the achievable precision.

scholarly journals PHANTOM ACCRETION BY FIVE-DIMENSIONAL CHARGED BLACK HOLE

2011 ◽  
Vol 26 (23) ◽  
pp. 1731-1736 ◽  
Author(s):  
M. SHARIF ◽  
G. ABBAS
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Equations Of Motion ◽  
Dynamical Behavior ◽  
Naked Singularity ◽  
Phantom Energy ◽  
Charge Ratio ◽  
Charged Black Hole ◽  
Spherically Symmetric ◽  
Symmetric Flow

This paper deals with the dynamical behavior of phantom field near five-dimensional charged black hole. We formulate equations of motion for steady-state spherically symmetric flow of phantom fluids. It is found that phantom energy accretes onto black holes for u < 0. Further, the location of critical point of accretion are evaluated that leads to mass to charge ratio for 5D charged black hole. This ratio implies that accretion cannot transform a black hole into a naked singularity. We would like to mention here that this work is an irreducible extension of 4D charged black hole.

scholarly journals Classical Limit for Dirac Fermions with Modified Action in the Presence of a Black Hole

Symmetry ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1294
Author(s):  
Meir Lewkowicz ◽  
Mikhail Zubkov
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Fermi Surface ◽  
Gravitational Collapse ◽  
Classical Limit ◽  
Numerical Solutions ◽  
Equations Of Motion ◽  
Einstein Equations ◽  
Covariant Formulation ◽  
Dirac Fermions

We consider the model of Dirac fermions coupled to gravity as proposed, in which superluminal velocities of particles are admitted. In this model an extra term is added to the conventional Hamiltonian that originates from Planck physics. Due to this term, a closed Fermi surface is formed in equilibrium inside the black hole. In this paper we propose the covariant formulation of this model and analyse its classical limit. We consider the dynamics of gravitational collapse. It appears that the Einstein equations admit a solution identical to that of ordinary general relativity. Next, we consider the motion of particles in the presence of a black hole. Numerical solutions of the equations of motion are found which demonstrate that the particles are able to escape from the black hole.

scholarly journals Charged and Non-Charged Black Hole Solutions in Mimetic Gravitational Theory

Symmetry ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 559 ◽  
Author(s):  
Gamal Nashed
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Gravitational Theory ◽  
Relativity Theory ◽  
Charged Black Hole ◽  
Field Equations ◽  
General Relativity Theory ◽  
Mimetic Theory ◽  
Black Hole Solutions

In this study, we derive, in the framework of mimetic theory, charged and non-charged black hole solutions for spherically symmetric as well as flat horizon spacetimes. The asymptotic behavior of those black holes behave as flat or (A)dS spacetimes and coincide with the solutions derived before in general relativity theory. Using the field equations of non-linear electrodynamics mimetic theory we derive new black hole solutions with monopole and quadrupole terms. The quadruple term of those black holes is related by a constant so that its vanishing makes the solutions coincide with the linear Maxwell black holes. We study the singularities of those solutions and show that they possess stronger singularity than the ones known in general relativity. Among many things, we study the horizons as well as the heat capacity to see if the black holes derived in this study have thermodynamical stability or not.

scholarly journals Re-scaling of energy in stringy charged black hole solutions using approximate symmetries

2010 ◽  
Vol 88 (11) ◽  
pp. 833-839 ◽  
Author(s):  
M. Sharif ◽  
Saira Waheed
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Order Approximation ◽  
Lie Symmetry ◽  
Second Order ◽  
Charged Black Hole ◽  
Energy Problem ◽  
Approximate Symmetries ◽  
Stringy Charged Black Hole ◽  
Black Hole Solutions

This paper examines the energy problem in General Relativity using approximate Lie symmetry methods for differential equations. We evaluate second-order approximate symmetries of the geodesic equations for the stringy charged black hole solutions. We conclude that energy must be re-scaled by some factor in the second-order approximation.

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