Rotating charged black hole spacetimes in quadratic f(R) gravitational theories

2018 ◽  
Vol 27 (07) ◽  
pp. 1850074 ◽  
Author(s):  
G. G. L. Nashed
Keyword(s):  
Black Holes ◽  
Energy Condition ◽  
Energy Conditions ◽  
Conserved Quantities ◽  
De Sitter ◽  
Black Hole Spacetimes ◽  
Symmetric Spacetimes ◽  
Gravitational Theories ◽  
Sitter Spacetime ◽  
General Vector

Motivated by the substantial modifications of gravitational theories and by the models that come out of [Formula: see text], we apply the field equation of the charged [Formula: see text] as well as a general vector potential containing three unknown functions to two spherically symmetric spacetimes. We solve the output of the differential equations and derive a class of black holes that are electrically and magnetically rotating spacetimes. The asymptotic behavior of these black holes acts as anti-de Sitter spacetime. Moreover, these solutions have asymptotic curvature singularities as those of General Relativity. We investigate this by calculating the invariants of curvature. Also, we address the issue of the energy conditions and show that the strong energy condition is satisfied provided [Formula: see text]. Finally, we compute the conserved quantities like mass and angular momentum.

scholarly journals Higher Dimensional Charged Black Hole Solutions in f(R) Gravitational Theories

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
G. G. L. Nashed
Keyword(s):  
Interesting Property ◽  
Conserved Quantities ◽  
Specific Class ◽  
De Sitter Spacetime ◽  
Cauchy Horizon ◽  
De Sitter ◽  
Gravitational Theories ◽  
Sitter Spacetime ◽  
Higher Dimensional ◽  
The Magnetic Field

We present, without any assumption, a class of electric and magnetic flat horizon D-dimension solutions for a specific class of f(R)=R+αR2, all of which behave asymptotically as Anti-de-Sitter spacetime. The most interesting property of these solutions is that the higher dimensions black holes, D>4, always have constant electric and magnetic charges in contrast to what is known in the literature. For D=4, we show that the magnetic field participates in the metric on equal foot as the electric field participates. Another interesting result is the fact that the Cauchy horizon is not identical with the event horizon. We use Komar formula to calculate the conserved quantities. We study the singularities and calculate the Hawking temperature and entropy and show that the first law of thermodynamics is always satisfied.

scholarly journals Traversable wormholes in Einsteinian cubic gravity

2019 ◽  
Vol 35 (06) ◽  
pp. 2050017 ◽  
Author(s):  
Mohammad Reza Mehdizadeh ◽  
Amir Hadi Ziaie
Keyword(s):  
Equation Of State ◽  
Gravitational Lensing ◽  
Energy Condition ◽  
Higher Order ◽  
Energy Conditions ◽  
Geodesic Motion ◽  
De Sitter ◽  
Asymptotically Flat ◽  
Traversable Wormholes ◽  
Standard Energy

In this work, we investigate wormhole configurations described by a constant redshift function in Einstein-Cubic gravity ( ECG ). We derive analytical wormhole geometries by assuming a particular equation of state ( EoS ) and investigate the possibility that these solutions satisfy the standard energy conditions. We introduce exact asymptotically flat and anti-de Sitter (AdS) spacetimes that admit traversable wormholes. These solutions are obtained by imposing suitable values for the parameters of the theory so that the resulted geometries satisfy the weak energy condition ( WEC ) in the vicinity of the throat, due to the presence of higher-order curvature terms. Moreover, we find that AdS solutions satisfy the WEC throughout the spacetime. A description of the geodesic motion of time-like and null particles is presented for the obtained wormhole solutions. Also, using gravitational lensing effects, observational features of the wormhole structure are discussed.

scholarly journals HIGHER DIMENSIONAL INHOMOGENEOUS DUST COLLAPSE AND COSMIC CENSORSHIP

2002 ◽  
Vol 17 (20) ◽  
pp. 2747-2747
Author(s):  
A. BEESHAM
Keyword(s):  
Black Holes ◽  
Cosmic Censorship ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Naked Singularities ◽  
Singularity Theorems ◽  
Sitter Spacetime ◽  
Higher Dimensional ◽  
Cosmic Censorship Hypothesis ◽  
Strong Curvature

The singularity theorems of general relativity predict that gravitational collapse finally ends up in a spacetime singularity1. The cosmic censorship hypothesis (CCH) states that such a singularity is covered by an event horizon2. Despite much effort, there is no rigorous formulation or proof of the CCH. In view of this, examples that appear to violate the CCH and lead to naked singularities, in which non-spacelike curves can emerge, rather than black holes, are important to shed more light on the issue. We have studied several collapse scenarios which can lead to both situations3. In the case of the Vaidya-de Sitter spacetime4, we have shown that the naked singularities that arise are of the strong curvature type. Both types of singularities can also arise in higher dimensional Vaidya and Tolman-Bondi spacetimes, but black holes are favoured in some sense by the higher dimensions. The charged Vaidya-de Sitter spacetime also exhibits both types of singularities5.

scholarly journals Charged anti-de Sitter BTZ black holes in Maxwell-f(T) gravity

2018 ◽  
Vol 33 (13) ◽  
pp. 1850076 ◽  
Author(s):  
G. G. L. Nashed ◽  
S. Capozziello
Keyword(s):  
Black Holes ◽  
Special Form ◽  
Energy Content ◽  
Equations Of Motion ◽  
Main Task ◽  
Cauchy Horizon ◽  
De Sitter ◽  
Vector Form ◽  
Charged Case ◽  
General Vector

Inspired by the Bañados, Teitelboim and Zanelli (BTZ) formalism, we discuss the Maxwell-[Formula: see text] gravity in [Formula: see text] dimensions. The main task is to derive exact solutions for a special form of [Formula: see text], with [Formula: see text] being the torsion scalar of Weitzenböck geometry. To this end, a triad field is applied to the equations of motion of charged [Formula: see text] and sets of circularly symmetric noncharged and charged solutions have been derived. We show that, in the charged case, the monopole-like and the [Formula: see text] terms are linked by a correlative constant despite the known results in teleparallel geometry and its extensions.[Formula: see text] Furthermore, it is possible to show that the event horizon is not identical with the Cauchy horizon due to such a constant. The singularities and the horizons of these black holes are examined: they are new and have no analogue in the literature due to the fact that their curvature singularities are soft. We calculate the energy content of these solutions by using the general vector form of the energy–momentum within the framework of [Formula: see text] gravity. Finally, some thermodynamical quantities, like entropy and Hawking temperature, are derived.

scholarly journals Conserved quantities and dual turbulent cascades in anti–de Sitter spacetime

2015 ◽  
Vol 91 (6) ◽  
Author(s):  
Alex Buchel ◽  
Stephen R. Green ◽  
Luis Lehner ◽  
Steven L. Liebling
Keyword(s):  
Conserved Quantities ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Sitter Spacetime

scholarly journals Tunneling across dilaton coupled black holes in anti de Sitter spacetime

2011 ◽  
Vol 696 (1-2) ◽  
pp. 167-172 ◽  
Author(s):  
Tanwi Ghosh ◽  
Soumitra SenGupta
Keyword(s):  
Black Holes ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Sitter Spacetime

scholarly journals NONSTATIC CHARGED BTZ-LIKE BLACK HOLES IN N+1 DIMENSIONS

2012 ◽  
Vol 21 (03) ◽  
pp. 1250022 ◽  
Author(s):  
SUSHANT G. GHOSH
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Collapse ◽  
Naked Singularity ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Btz Black Hole ◽  
Sitter Spacetime ◽  
Apparent Horizons ◽  
Sitter Background

We find an exact nonstatic charged BTZ-like solutions, in (N+1)-dimensional Einstein gravity in the presence of negative cosmological constant and a nonlinear Maxwell field defined by a power s of the Maxwell invariant, which describes the gravitational collapse of charged null fluid in an anti-de Sitter background. Considering the situation that a charged null fluid injects into the initially an anti-de Sitter spacetime, we show that a black hole form rather than a naked singularity, irrespective of spacetime dimensions, from gravitational collapse in accordance with cosmic censorship conjecture. The structure and locations of the apparent horizons of the black holes are also determined. It is interesting to see that, in the static limit and when N = 2, one can retrieve 2+1 BTZ black hole solutions.

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