scholarly journals Reissner–Nordstrom metric in unimodular theory of gravity

2017 ◽  
Vol 26 (08) ◽  
pp. 1750082 ◽  
Author(s):  
Pankaj Chaturvedi ◽  
Naveen K. Singh ◽  
Dharm Veer Singh
Keyword(s):  
Black Hole ◽  
Maxwell Equations ◽  
Black Hole Solution ◽  
Magnetic Charge ◽  
Einstein Field Equation ◽  
Einstein Gravity ◽  
Thermodynamical Properties ◽  
Electromagnetic Field Strength ◽  
Strength Tensor ◽  
Gravitational Background

We study the modified Reissner–Nordstrom (RN) metric in the unimodular gravity. So far the spherical symmetric Einstein field equation in unimodular gravity has been studied in the absence of any source. We consider static electric and magnetic charge as source. We solve for Maxwell equations in unimodular gravitational background. We show that in unimodular gravity, the electromagnetic field strength tensor is modified. We also show that the solution in unimodular gravity differs from the usual RN metric in Einstein gravity with some corrections. We further study the thermodynamical properties of the RN black hole solution in this theory.

scholarly journals THERMODYNAMICAL PROPERTIES AND QUASI-LOCALIZED ENERGY OF THE STRINGY DYONIC BLACK HOLE SOLUTION

2012 ◽  
Vol 27 (29) ◽  
pp. 1250169 ◽  
Author(s):  
I-CHING YANG ◽  
BAI-AN CHEN ◽  
CHUNG-CHIN TSAI
Keyword(s):  
Heat Flux ◽  
Black Hole ◽  
Black Hole Solution ◽  
Dual Transformation ◽  
Outer Horizon ◽  
Thermodynamical Properties ◽  
Inner Horizon ◽  
The Difference

In this paper, we calculate the heat flux passing through the horizon TS|rh and the difference of energy between the Einstein and Møller prescription within the region [Formula: see text], in which is the region between outer horizon [Formula: see text] and inner horizon [Formula: see text], for the modified GHS solution, KLOPP solution and CLH solution. The formula [Formula: see text]TS is obeyed for the mGHS solution and the KLOPP solution, but not for the CLH solution. Also, we suggest a RN-like stringy dyonic black hole solution, which comes from the KLOPP solution under a dual transformation, and its thermodynamical properties are the same as the KLOPP solution.

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.

scholarly journals N=2 SUPERSYMMETRY AND STRING-LOOP CORRECTED MAGNETIC BLACK HOLES

2002 ◽  
Vol 17 (06) ◽  
pp. 355-371 ◽  
Author(s):  
MIKHAIL Z. IOFA
Keyword(s):  
Black Hole ◽  
Maxwell Equations ◽  
Black Hole Solution ◽  
Equations Of Motion ◽  
Level Gauge ◽  
Tree Level ◽  
Loop Correction ◽  
Heterotic String Theory ◽  
String Loop ◽  
Gauge Couplings

We study string-loop corrections to magnetic black hole. Four-dimensional theory is obtained by compactification of the heterotic string theory on the manifold K3×T2 or on a suitable orbifold yielding N=1 supersymmetry in 6D. The resulting 4D theory has N=2 local supersymmetry. Prepotential of this theory receives only one-string-loop correction. The tree-level gauge couplings are proportional to the inverse effective string coupling and decrease at small distances from the center of magnetic black hole, so that loop corrections to the gauge couplings are important in this region. We solve the system of Killing spinor equations (conditions for the supersymmetry variations of the fermions to vanish) and Maxwell equations. At the string-tree level, we reproduce the magnetic black hole solution which can also be obtained by solving the system of the Einstein–Maxwell equations and the equations of motion for the moduli. String-loop corrections to the tree-level solution are calculated in the first order in string coupling. The resulting corrections to the metric and dilaton are large at small distances from the center of the black hole. Possible smearing of the singularity at the origin by quantum corrections is discussed.

scholarly journals Einstein and Møller Energy-Momentum Complexes for a New Regular Black Hole Solution with a Nonlinear Electrodynamics Source

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Irina Radinschi ◽  
Farook Rahaman ◽  
Theophanes Grammenos ◽  
Sayeedul Islam
Keyword(s):  
Black Hole ◽  
Black Hole Solution ◽  
Relevant Literature ◽  
Nonlinear Electrodynamics ◽  
Radial Coordinate ◽  
Schwarzschild Black Hole ◽  
Regular Black Hole ◽  
Momentum Distributions ◽  
Energy And Momentum ◽  
Gravitational Background

A study about the energy and momentum distributions of a new charged regular black hole solution with a nonlinear electrodynamics source is presented. The energy and momentum are calculated using the Einstein and Møller energy-momentum complexes. The results show that in both pseudotensorial prescriptions the expressions for the energy of the gravitational background depend on the massMand the chargeqof the black hole, an additional factorβcoming from the spacetime metric considered, and the radial coordinater, while in both prescriptions all the momenta vanish. Further, it is pointed out that in some limiting and particular cases the two complexes yield the same expression for the energy distribution as that obtained in the relevant literature for the Schwarzschild black hole solution.

Scalar and Dirac quasinormal modes of the scalar-tensor-Gauss-Bonnet black holes

2021 ◽  
Author(s):  
Tongzheng Wang ◽  
Wei-Liang Qian ◽  
Juan Fernando Zapata Zapata ◽  
Kai Lin
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Black Hole Solution ◽  
Magnetic Charge ◽  
Quasinormal Modes ◽  
Analytic Solutions ◽  
Adm Mass ◽  
Black Hole Spacetimes ◽  
Different Types ◽  
The Stability

Abstract This work explores the scalar and Dirac quasinormal modes pertaining to a class of black hole solutions in the scalar-tensor-Gauss-Bonnet theory. The black hole metrics in question are novel analytic solutions recently derived in the extended version of the latter theory, which effectively follows at the level of the action of string theory. Owing to the existence of a nonlinear electromagnetic field, the black hole solution possesses a nonvanishing magnetic charge. In particular, the metric is capable of describing black holes with distinct characteristics by assuming different values of the ADM mass and the magnetic charge. The present study is devoted to investigating the scalar and Dirac perturbations in the above black hole spacetimes, and in particular, based on distinct horizon structures, we focus on two different types of solutions. The properties of the complex frequencies of the obtained dissipative oscillations are investigated, and subsequently, the stability of the metric is addressed. We elaborate on the possible implications of the present study.

scholarly journals New five-dimensional Bianchi type magnetically charged hairy topological black hole solutions in string theory

2019 ◽  
Vol 79 (12) ◽  
Author(s):  
F. Naderi ◽  
A. Rezaei-Aghdam
Keyword(s):  
Black Hole ◽  
Black Hole Solution ◽  
Bianchi Type ◽  
Magnetic Charge ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Five Dimensions ◽  
Asymptotically Flat ◽  
Black Hole Solutions ◽  
Three Dimensional Space

AbstractWe construct black hole solutions to the leading order of string effective action in five dimensions with the source given by dilaton and magnetically charged antisymmetric gauge B-field. Presence of the considered B-field leads to the unusual asymptotic behavior of the solutions which are neither asymptotically flat nor asymptotically (A)dS. We consider the three-dimensional space part to correspond to the Bianchi classes and so the horizons of these topological black hole solutions are modeled by seven homogeneous Thurston’s geometries of $$E^3$$E3, $$S^3$$S3, $$H^3$$H3, $$ H^2 \times E^1$$H2×E1, $$\widetilde{{SL_2R}}$$SL2R~, nilgeometry, and solvegeometry. Calculating the quasi-local mass, temperature, entropy, dilaton charge, and magnetic potential, we show that the first law of black hole thermodynamics is satisfied by these quantities and the dilaton charge is not independent of mass and magnetic charge. Furthermore, for Bianchi type V, the T-dual black hole solution is obtained which carries no charge associated with B-field and the entropy turns to be invariant under the T-duality.

scholarly journals Remark on near-horizon geometry of extreme regular black holes

2018 ◽  
Vol 33 (34) ◽  
pp. 1850197
Author(s):  
Sergei Filyukov
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Black Hole Solution ◽  
Einstein Gravity ◽  
Nonlinear Electrodynamics ◽  
Regular Black Hole ◽  
Regular Black Holes ◽  
Horizon Geometry

It is shown that the near-horizon geometry of a generic extreme regular black hole solution of Einstein gravity coupled to nonlinear electrodynamics is described by the AdS2 × S2 spacetime.

INFLUENCE OF MAGNETIC CHARGE ON THE SAGNAC EFFECT IN THE BARDEEN SPACETIME

2021 ◽  
Vol 0 (1) ◽  
pp. 92-96
Author(s):  
R.KH. KARIMOV ◽  
◽  
K.K. NANDI ◽  
Keyword(s):  
Black Hole ◽  
Light Source ◽  
Magnetic Charge ◽  
Sagnac Effect ◽  
Modified Theories Of Gravity ◽  
Circular Orbits ◽  
The Earth ◽  
Astrophysical Objects ◽  
Interesting Task ◽  
Theories Of Gravity

This paper investigates one of the most interesting effects associated with the rotation of astrophysical objects (the Sagnac effect). The effect was first confirmed in laboratory experiments by Georges Sagnac with a rotating ring interferometer in 1913. Later, the effect was also confirmed within the framework of the Earth in the "Around-the-World" experiment conducted by J. Hafele and R. Kitting, in which they twice circled the Earth with an atomic cesium clock on board and compared the "flying" clock with those remaining static on the Earth. As a result, a non-zero difference in the clock rate was found as a confirmation of the Sagnac effect. Subsequently, more precise satellite experiments have been carried out to measure the Sagnac effect within the Earth. The effect was also considered in general relativity and modified theories of gravity, where many works were carried out to study the influence of such parameters as angular momentum, cosmological constant, Ricci scalar, etc. on the Sagnac effect. An interesting task is to study the influence of a magnetic charge on the effect, since the solution with rotation described by a black hole with mass M and magnetic charge g is the Bardeen nonsingular black hole. The work will calculate the Sagnac effect in the space-time of the rotating Bardeen black hole for both geodesic and non-geodesic circular orbits of the light source / receiver (assuming that the light source and receiver are defined at the same point). Two types of circular orbits describe the opposing influence on the Sagnac effect: the Sagnac delay increases with an increase in the magnetic charge in the case of non-geodesic circular orbits and decreases in the case of geodesic circular orbits. However, the farther is the orbit of the light source / receiver, the less the magnetic charge affects the Sagnac delay. It is also assumed that the gravity of the Earth and the Sun near the surface is well described by the Bardeen metric.

scholarly journals ON KALUZA–KLEIN SPACE–TIME IN EINSTEIN–GAUSS–BONNET GRAVITY

2009 ◽  
Vol 18 (04) ◽  
pp. 599-611 ◽  
Author(s):  
ALFRED MOLINA ◽  
NARESH DADHICH
Keyword(s):  
Black Hole ◽  
Black Hole Solution ◽  
Dimensional Space ◽  
Space Time ◽  
Two Dimensional ◽  
Bonnet Gravity ◽  
Space Of Constant Curvature ◽  
Dimensional Black Hole ◽  
Dimensional Space Time ◽  
Kaluza Klein

By considering the product of the usual four-dimensional space–time with two dimensional space of constant curvature, an interesting black hole solution has recently been found for Einstein–Gauss–Bonnet gravity. It turns out that this as well as all others could easily be made to radiate Vaidya null dust. However, there exists no Kerr analog in this setting. To get the physical feel of the four-dimensional black hole space–times, we study asymptotic behavior of stresses at the two ends, r → 0 and r → ∞.

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