New black hole solutions of Einstein field equations and their Riemann curvature tensors

2015 ◽  
Vol 30 (06) ◽  
pp. 1550028 ◽  
Author(s):  
Farhad Ali
Keyword(s):  
Black Hole ◽  
Riemann Curvature ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Cylindrically Symmetric ◽  
Symmetric Black Hole ◽  
Curvature Tensors ◽  
Black Hole Solutions

Here, we are going to discuss some new cases of cylindrically symmetric black hole solutions of Einstein field equations (EFEs). These are new solutions which we have not seen in the literature. We also listed their Riemann curvature tensors.

Asymptotically flat black hole solutions in quadratic gravity

2021 ◽  
pp. 2142015
Author(s):  
Frank Saueressig ◽  
Mina Galis ◽  
Jesse Daas ◽  
Amir Khosravi
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Field Equations ◽  
Schwarzschild Solution ◽  
Asymptotically Flat ◽  
Singularity Theorems ◽  
Dead End ◽  
Quadratic Gravity ◽  
Symmetric Black Hole ◽  
Black Hole Solutions

Black holes constitute some of the most fascinating objects in our universe. According to Einstein’s theory of general relativity, they are also deceivingly simple: Schwarzschild black holes are completely determined by their mass. Moreover, the singularity theorems by Penrose and Hawking indicate that they host a curvature singularity within their event horizon. The presence of the latter invites the question whether these dead-end points of spacetime can be made regular by considering (quantum) corrections to the classical field equations. In this light, we use the Frobenius method to investigate the phase space of asymptotically flat, static, and spherically symmetric black hole solutions in quadratic gravity. We argue that the only asymptotically flat black hole solution visible in this approach is the Schwarzschild solution.

scholarly journals On the gravitational entropy of accelerating black holes

2020 ◽  
Vol 29 (05) ◽  
pp. 2050034
Author(s):  
Sarbari Guha ◽  
Samarjit Chakraborty
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Phenomenological Approach ◽  
Entropy Density ◽  
Charged Black Hole ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Gravitational Entropy ◽  
Definition Of ◽  
Black Hole Solutions

In this paper, we have examined the validity of a proposed definition of gravitational entropy in the context of accelerating black hole solutions of the Einstein field equations, which represent the realistic black hole solutions. We have adopted a phenomenological approach proposed in Rudjord et al. [Phys. Scr. 77, 055901 (2008)] and expanded by Romero et al. [Int. J. Theor. Phys. 51, 925 (2012)], in which the Weyl curvature hypothesis is tested against the expressions for the gravitational entropy. Considering the [Formula: see text]-metric for the accelerating black holes, we have evaluated the gravitational entropy and the corresponding entropy density for four different types of black holes, namely, nonrotating black hole, nonrotating charged black hole, rotating black hole and rotating charged black hole. We end up by discussing the merits of such an analysis and the possible reason of failure in the particular case of rotating charged black hole and comment on the possible resolution of the problem.

scholarly journals Thermodynamics and reentrant phase transition for logarithmic nonlinear charged black holes in massive gravity

2020 ◽  
Vol 29 (12) ◽  
pp. 2050081
Author(s):  
S. Rajaee Chaloshtary ◽  
M. Kord Zangeneh ◽  
S. Hajkhalili ◽  
A. Sheykhi ◽  
S. M. Zebarjad
Keyword(s):  
Phase Transition ◽  
Black Holes ◽  
Black Hole ◽  
Quantum Effect ◽  
Massive Gravity ◽  
Nonlinear Electrodynamics ◽  
Model Parameters ◽  
Thermodynamic Quantities ◽  
Field Equations ◽  
Black Hole Solutions

We investigate a new class of [Formula: see text]-dimensional topological black hole solutions in the context of massive gravity and in the presence of logarithmic nonlinear electrodynamics. Exploring higher-dimensional solutions in massive gravity coupled to nonlinear electrodynamics is motivated by holographic hypothesis as well as string theory. We first construct exact solutions of the field equations and then explore the behavior of the metric functions for different values of the model parameters. We observe that our black holes admit the multi-horizons caused by a quantum effect called anti-evaporation. Next, by calculating the conserved and thermodynamic quantities, we obtain a generalized Smarr formula. We find that the first law of black holes thermodynamics is satisfied on the black hole horizon. We study thermal stability of the obtained solutions in both canonical and grand canonical ensembles. We reveal that depending on the model parameters, our solutions exhibit a rich variety of phase structures. Finally, we explore, for the first time without extending thermodynamics phase space, the critical behavior and reentrant phase transition for black hole solutions in massive gravity theory. We realize that there is a zeroth-order phase transition for a specified range of charge value and the system experiences a large/small/large reentrant phase transition due to the presence of nonlinear electrodynamics.

scholarly journals TRAPPING PHOTONS BY A LINE SINGULARITY

2003 ◽  
Vol 12 (06) ◽  
pp. 1095-1112 ◽  
Author(s):  
METIN ARIK ◽  
OZGUR DELICE
Keyword(s):  
Energy Density ◽  
Thin Shell ◽  
Energy Momentum Tensor ◽  
Momentum Tensor ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Cylindrically Symmetric ◽  
Static Solutions ◽  
Line Singularity ◽  
Thick Shells

We present cylindrically symmetric, static solutions of the Einstein field equations around a line singularity such that the energy momentum tensor corresponds to infinitely thin photonic shells. Positivity of the energy density of the thin shell and the line singularity is discussed. It is also shown that thick shells containing mostly radiation are possible in a numerical solution.

ON (2+2)-DIMENSIONAL SPACE–TIMES, STRINGS AND BLACK HOLES

2007 ◽  
Vol 22 (11) ◽  
pp. 2021-2045 ◽  
Author(s):  
C. CASTRO ◽  
J. A. NIETO
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Homogeneous Spaces ◽  
Dimensional Space ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Dimensional Solution ◽  
Complex Dimensions ◽  
Dimensional Space Time ◽  
Dimensional Boundary

We study black hole-like solutions (space–times with singularities) of Einstein field equations in 3+1 and 2+2 dimensions. We find three different cases associated with hyperbolic homogeneous spaces. In particular, the hyperbolic version of Schwarzschild's solution contains a conical singularity at r = 0 resulting from pinching to zero size r = 0 the throat of the hyperboloid [Formula: see text] and which is quite different from the static spherically symmetric (3+1)-dimensional solution. Static circular symmetric solutions for metrics in 2+2 are found that are singular at ρ = 0 and whose asymptotic ρ→∞ limit leads to a flat (1+2)-dimensional boundary of topology S1 × R2. Finally we discuss the (1+1)-dimensional Bars–Witten stringy black hole solution and show how it can be embedded into our (3+1)-dimensional solutions. Black holes in a (2+2)-dimensional "space–time" from the perspective of complex gravity in 1+1 complex dimensions and their quaternionic and octonionic gravity extensions deserve furher investigation. An appendix is included with the most general Schwarzschild-like solutions in D ≥ 4.

scholarly journals A new type of nonsingular black-hole solution in general relativity

2014 ◽  
Vol 29 (19) ◽  
pp. 1430018 ◽  
Author(s):  
F. R. Klinkhamer
Keyword(s):  
Black Hole ◽  
Spherically Symmetric ◽  
Curvature Singularity ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Schwarzschild Solution ◽  
Gravity Effects ◽  
New Type ◽  
Nontrivial Topology ◽  
Spacetime Foam

Certain exact solutions of the Einstein field equations over nonsimply-connected manifolds are reviewed. These solutions are spherically symmetric and have no curvature singularity. They provide a regularization of the standard Schwarzschild solution with a curvature singularity at the center. Spherically symmetric collapse of matter in ℝ4 may result in these nonsingular black-hole solutions, if quantum-gravity effects allow for topology change near the center or if nontrivial topology is already present as a remnant from a quantum spacetime foam.

scholarly journals The ‘non-Kerrness’ of domains of outer communication of black holes and exteriors of stars

2011 ◽  
Vol 467 (2130) ◽  
pp. 1701-1718 ◽  
Author(s):  
Thomas Bäckdahl ◽  
Juan A. Valiente Kroon
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Three Dimensional ◽  
Dimensional Manifold ◽  
Geometric Invariant ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Kerr Spacetime ◽  
Killing Spinors ◽  
Initial Dataset

In this paper, we construct a geometric invariant for initial datasets for the vacuum Einstein field equations , such that is a three-dimensional manifold with an asymptotically Euclidean end and an inner boundary with the topology of the 2-sphere. The hypersurface can be thought of being in the domain of outer communication of a black hole or in the exterior of a star. The geometric invariant vanishes if and only if is an initial dataset for the Kerr spacetime. The construction makes use of the notion of Killing spinors and of an expression for a Killing spinor candidate , which can be constructed out of concomitants of the Weyl tensor.

Spherically symmetric black hole solution in mimetic gravity and anti-evaporation

2018 ◽  
Vol 15 (09) ◽  
pp. 1850154 ◽  
Author(s):  
G. G. L. Nashed
Keyword(s):  
Black Hole ◽  
Black Hole Solution ◽  
Spherically Symmetric ◽  
Mimetic Theory ◽  
Event Horizons ◽  
Flat Spacetime ◽  
Symmetric Black Hole ◽  
The Stability ◽  
Mimetic Gravity ◽  
Black Hole Solutions

In this paper, we study the mimetic theory and derive a new spherically symmetric black hole solution. The asymptotic behavior of this solution behaves as a flat spacetime. This black hole is characterized by the fact that it has different components of [Formula: see text] and [Formula: see text]. Nevertheless, both of these components have a coinciding Killing and event horizons. Furthermore, this black hole has curvature singularities which are stronger than those of the known black hole solutions in general relativity. This feature can be shown by calculating some invariants of curvature. We study the stability of the perturbation and the related anti-evaporation of the Nariai spacetime.

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