scholarly journals Black hole solutions in Rastall theory

2017 ◽  
Vol 95 (12) ◽  
pp. 1253-1256 ◽  
Author(s):  
Y. Heydarzade ◽  
H. Moradpour ◽  
F. Darabi
Keyword(s):  
Black Hole ◽  
General Solution ◽  
Symmetric Space ◽  
Cosmological Constant ◽  
Black Hole Solution ◽  
Ad Hoc ◽  
Vacuum Field ◽  
De Sitter ◽  
Field Equations ◽  
Black Hole Solutions

The Reissner–Nordström black hole solution in a generic cosmological constant background in the context of Rastall gravity is obtained. It is shown that the cosmological constant arises naturally from the consistency of the non-vacuum field equations of the Rastall theory for a spherical symmetric space–time, rather than its ad hoc introduction in the usual Einstein and Einstein–Maxwell field equations. The usual Reissner–Nordström, Schwarzschild, and Schwarzschild – (anti-)de Sitter black hole solutions in the framework of this theory are also addressed as the special independent subclasses of the obtained general solution.

scholarly journals Exact black hole solutions with nonlinear electrodynamic field

2020 ◽  
Vol 29 (05) ◽  
pp. 2050032
Author(s):  
Shuang Yu ◽  
Changjun Gao
Keyword(s):  
Black Hole ◽  
Cosmological Constant ◽  
Electric Charge ◽  
Single Phase ◽  
Causal Structure ◽  
Nonlinear Electrodynamic ◽  
Coupling Constant ◽  
De Sitter ◽  
Black Hole Solutions ◽  
Three Phases

We construct exact black hole solutions to Einstein gravity with nonlinear electrodynamic field. In these solutions, there are, in general, four parameters. They are physical mass, electric charge, cosmological constant and the coupling constant. These solutions differ significantly from the Reissner–Nordström–de Sitter solution in Einstein–Maxwell gravity with a cosmological constant, due to the presence of coupling constant. For example, some of them are endowed with a topological defect on angle [Formula: see text] and the electric charge of some can be much larger or smaller than their mass by varying the coupling constant. On the other hand, these spacetimes are all asymptotically de Sitter (or anti-de Sitter). As a result, their causal structure is similar to the Reissner–Nordström–de Sitter spacetime. Finally, the investigations on the thermodynamics reveal that the coupling constant except for solution-4 has the opposite effect as temperature on the phase, structure of black holes. Concretely, the phase-space changes from single phase to three phases with the decrease of temperature. On the contrary, it changes from three phases to a single phase with the decrease of coupling constant.

scholarly journals Exact charged black hole solutions in D-dimensions in f(R) gravity

2021 ◽  
Vol 81 (4) ◽  
Author(s):  
Zi-Yu Tang ◽  
Bin Wang ◽  
Eleftherios Papantonopoulos
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
General Solution ◽  
Constant Curvature ◽  
Black Hole Solution ◽  
Einstein Gravity ◽  
Charged Black Hole ◽  
Spherically Symmetric ◽  
Spherically Symmetric Metric ◽  
Black Hole Solutions

AbstractWe consider Maxwell-f(R) gravity and obtain an exact charged black hole solution with dynamic curvature in D-dimensions. Considering a spherically symmetric metric ansatz and without specifying the form of f(R) we find a general black hole solution in D-dimensions. This general black hole solution can reduce to the Reissner–Nordström (RN) black hole in D-dimensions in Einstein gravity and to the known charged black hole solutions with constant curvature in f(R) gravity. Restricting the parameters of the general solution we get polynomial solutions which reveal novel properties when compared to RN black holes. Specifically we study the solution in $$(3+1)$$ ( 3 + 1 ) -dimensions in which the form of f(R) can be solved explicitly giving a dynamic curvature and compare it with the RN black hole. We also carry out a detailed study of its thermodynamics.

THEOREM TO GENERATE NON-SPHERICAL RADIATING BLACK HOLE SOLUTIONS

2008 ◽  
Vol 23 (15) ◽  
pp. 1115-1127
Author(s):  
V. S. MOROZOVA ◽  
S. G. GHOSH
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cosmological Constant ◽  
Einstein Equations ◽  
Energy Conditions ◽  
Type I ◽  
De Sitter ◽  
Sitter Background ◽  
Two Parameter ◽  
Black Hole Solutions

We prove a theorem that characterizes a two-parameter family of solutions to Einstein equations with a negative cosmological constant, representing, in general, non-spherical radiating black holes in an anti-de Sitter background. It is shown that the best known non-spherical radiating black hole solutions are particular cases and static non-spherical black hole solutions, for Type I fluid, are also retrieved. A brief discussion on the energy conditions, singularities and horizons is provided.

scholarly journals Higher dimensional black hole solutions with scalar hair/dilaton field and Toroidal horizons and the interior solution

2021 ◽  
Author(s):  
Younes Younesizadeh ◽  
Yahya Younesizadeh
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Interior Solution ◽  
De Sitter ◽  
Field Equations ◽  
Higher Dimensional ◽  
Dimensional Black Hole ◽  
Scalar Hair ◽  
Special Case ◽  
Black Hole Solutions

In this paper we investigate the black hole solutions with toroidal horizons in scalar hair/dilaton gravity. First, we obtain the field equations in n-dimensions, then we propose some different models(Ansatz) and find the exact solutions for these type of ansatzs. These solutions are not asymptotically (anti-)de Sitter or flat, except in one special case. We also show that the BTZ and BTZ-like solutions will emerge from some of these solutions as a special case. We also show that when the event horizon radius gets bigger and bigger, the temperature will be the same in various dimensions. The only difference is noticeable near the origin(this statement is clear in diagrams). For these solutions, we obtained a new version of the Smarr formula as well. Also, we show that the presence of the scalar field makes the black holes to be more stable near the origin except for the BTZ case. We can say in general that the presence of scalar field is an important factor in black hole’s stability investigations. In the critical behavior analysis we find that there is no evidence to show the existence of P-V criticality. We present here a class of interior solutions corresponding to the solution in scalar hair gravity exterior. The solution which is obtained in linear case is regular and well-behaved at the stellar interior.

scholarly journals ROTATING BLACK HOLES IN METRIC-AFFINE GRAVITY

2006 ◽  
Vol 15 (05) ◽  
pp. 635-668 ◽  
Author(s):  
PETER BAEKLER ◽  
FRIEDRICH W. HEHL
Keyword(s):  
Black Hole Solution ◽  
Lorentz Invariance ◽  
Linear Connection ◽  
Vacuum Field ◽  
Axially Symmetric ◽  
De Sitter ◽  
Field Equations ◽  
Rotating Black Holes ◽  
Affine Gravity ◽  
De Sitter Metric

Within the framework of metric-affine gravity (MAG, metric and an independent linear connection constitute space–time), we find, for a specific gravitational Lagrangian and by using prolongation techniques, a stationary axially symmetric exact solution of the vacuum field equations. This black hole solution embodies a Kerr–de Sitter metric and the post-Riemannian structures of torsion and nonmetricity. The solution is characterized by mass, angular momentum, and shear charge, the latter of which is a measure for violating Lorentz invariance.

scholarly journals SKYRMION AND SKYRME-BLACK HOLES IN de SITTER SPACETIME

2006 ◽  
Vol 21 (27) ◽  
pp. 2043-2054 ◽  
Author(s):  
YVES BRIHAYE ◽  
TERENCE DELSATE
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cosmological Constant ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Positive Cosmological Constant ◽  
Asymptotically Flat ◽  
Sitter Spacetime ◽  
Black Hole Solutions

Numerical arguments are presented for the existence of regular and black hole solutions of the Einstein–Skyrme equations with a positive cosmological constant. These classical configurations approach asymptotically the de Sitter spacetime. The main properties of the solutions and the differences with respect to the asymptotically flat ones are discussed. In particular our results suggest that, for a positive cosmological constant, the mass evaluated as timelike infinity in infinite. Special emphasis is set to de Sitter black holes Skyrmions which display two horizons.

scholarly journals Gravitational Decoupling in Higher Order Theories

Symmetry ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1598
Author(s):  
Joseph Sultana
Keyword(s):  
Black Hole ◽  
Black Hole Solution ◽  
Scalar Fields ◽  
Higher Order ◽  
Vacuum Field ◽  
Field Equations ◽  
Simple Method ◽  
Seed Solution ◽  
Homotopy Analysis ◽  
Weyl Scalar

Gravitational decoupling via the Minimal Geometric Deformation (MGD) approach has been used extensively in General Relativity (GR), mainly as a simple method for generating exact anisotropic solutions from perfect fluid seed solutions. Recently this method has also been used to generate exact spherically symmetric solutions of the Einstein-scalar system from the Schwarzschild vacuum metric. This was then used to investigate the effect of scalar fields on the Schwarzschild black hole solution. We show that this method can be extended to higher order theories. In particular, we consider fourth order Einstein–Weyl gravity, and in this case by using the Schwarzschild metric as a seed solution to the associated vacuum field equations, we apply the MGD method to generate a solution to the Einstein–Weyl scalar theory representing a hairy black hole solution. This solution is expressed in terms of a series using the Homotopy Analysis Method (HAM).

General form of the analytic function f(T) in diverse dimension for a static planar spacetime

2019 ◽  
Vol 28 (12) ◽  
pp. 1950158 ◽  
Author(s):  
Gamal Nashed
Keyword(s):  
Black Hole ◽  
Analytic Function ◽  
Black Hole Solution ◽  
Static Solution ◽  
Gravitational Theory ◽  
Interesting Property ◽  
Constant Function ◽  
Field Equations ◽  
Adm Mass ◽  
Laws Of Thermodynamics

We derive an exact static solution in diverse dimension, without any constraints, to the field equations of [Formula: see text] gravitational theory using a planar spacetime with two unknown functions, i.e. [Formula: see text] and [Formula: see text]. The black hole solution is characterized by two constants, [Formula: see text] and [Formula: see text], one is related to the mass of the black hole, [Formula: see text], and the other is responsible to make the solution deviate from the teleparallel equivalent of general relativity (TEGR). We show that the analytic function [Formula: see text] depends on the constant [Formula: see text] and becomes constant function when [Formula: see text] which corresponds to the TEGR case. The interesting property of this solution is the fact that it makes the singularity of the Kretschmann invariant much softer than the TEGR case. We calculate the energy of this black hole and show that it is equivalent to ADM mass. Applying a coordinate transformation, we derive a rotating black hole with nontrivial values of the torsion scalar and [Formula: see text]. Finally, we examine the physical properties of this black hole solution using the laws of thermodynamics and show that it has thermodynamical stability.

scholarly journals Extremal Cosmological Black Holes in Horndeski Gravity and the Anti-Evaporation Regime

Universe ◽  
2020 ◽  
Vol 6 (11) ◽  
pp. 210
Author(s):  
Ismael Ayuso ◽  
Diego Sáez-Chillón Gómez
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cosmological Constant ◽  
Linear Order ◽  
Scalar Tensor Theory ◽  
De Sitter ◽  
Tensor Theory ◽  
Effective Cosmological Constant ◽  
Cosmological Black Holes ◽  
Extremal Black Holes

Extremal cosmological black holes are analysed in the framework of the most general second order scalar-tensor theory, the so-called Horndeski gravity. Such extremal black holes are a particular case of Schwarzschild-De Sitter black holes that arises when the black hole horizon and the cosmological one coincide. Such metric is induced by a particular value of the effective cosmological constant and is known as Nariai spacetime. The existence of this type of solutions is studied when considering the Horndeski Lagrangian and its stability is analysed, where the so-called anti-evaporation regime is studied. Contrary to other frameworks, the radius of the horizon remains stable for some cases of the Horndeski Lagrangian when considering perturbations at linear order.

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