scholarly journals New Model of 4D Einstein–Gauss–Bonnet Gravity Coupled with Nonlinear Electrodynamics

Universe ◽  
2021 ◽  
Vol 7 (7) ◽  
pp. 249
Author(s):  
Sergey Il’ich Kruglov
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Symmetric Solution ◽  
Emission Rate ◽  
Quasinormal Modes ◽  
Black Hole Thermodynamics ◽  
Nonlinear Electrodynamics ◽  
Spherically Symmetric ◽  
Bonnet Gravity ◽  
Spherically Symmetric Solution

New spherically symmetric solution in 4D Einstein–Gauss–Bonnet gravity coupled with nonlinear electrodynamics is obtained. At infinity, this solution has the Reissner–Nordström behavior of the charged black hole. The black hole thermodynamics, entropy, shadow, energy emission rate, and quasinormal modes of black holes are investigated.

scholarly journals 4D Einstein-Gauss-Bonnet Gravity Coupled with Nonlinear Electrodynamics

2020 ◽  
Author(s):  
Sergey Kruglov
Keyword(s):  
Black Holes ◽  
Heat Capacity ◽  
Black Hole ◽  
Phase Transitions ◽  
Black Hole Solution ◽  
Hawking Temperature ◽  
Nonlinear Electrodynamics ◽  
Nonlinearity Parameter ◽  
Spherically Symmetric ◽  
Bonnet Gravity

An exact spherically symmetric and magnetically charged black hole solution in 4D Einstein-Gauss-Bonnet gravity coupled to nonlinear electrodynamics (NED) is obtained. The NED Lagrangian is given by ${\cal L}_{NED} = -{\cal F}/(1+\sqrt[4]{2\beta{\cal F}})$, where ${\cal F}$ is the field invariant. We study the thermodynamics calculating the Hawking temperature and the heat capacity of the black hole. The phase transitions take place when the Hawking temperature has an extremum and the heat capacity is singular. We demonstrate that black holes are thermodynamically stable in some range of event horizon radii where the heat capacity is positive. The BH shadow radii are calculated. It is shown that when increasing the nonlinearity parameter $\beta$ the BH shadow radius is decreased.

Extended GUP corrected thermodynamics, shadow radius and quasinormal modes of charged AdS black holes in Gauss–Bonnet gravity

2021 ◽  
pp. 2150137
Author(s):  
Shahid Chaudhary ◽  
Abdul Jawad ◽  
Kimet Jusufi ◽  
Muhammad Yasir
Keyword(s):  
Black Hole ◽  
Generalized Uncertainty Principle ◽  
Quasinormal Modes ◽  
Nonlinear Electrodynamics ◽  
Horizon Radius ◽  
Bonnet Gravity ◽  
Ads Black Holes ◽  
Dimensional Black Hole ◽  
Relationship Of ◽  
The Relationship

This paper explores the influence of special type of higher order generalized uncertainty principle on the thermodynamics of five-dimensional black hole in Einstein–Gauss–Bonnet gravity coupled to nonlinear electrodynamics. We examine the corrected thermodynamical properties of the black hole with some interesting limiting cases [Formula: see text] and [Formula: see text] and compared our results with usual thermodynamical relations. We observe that the influence of GUP correction stabilizes the BH and BH solution remains physical throughout the region of horizon radius. In this framework, we also uncover the relationship of shadow radius and quasinormal modes of the mentioned black hole. We conclude that shadow radius of our considered black hole is a perfect circle and it decreases with increasing values of charge and Gauss–Bonnet parameter. We also verify the inverse relation between the quasinormal modes frequencies and shadow radius, i.e. quasinormal modes should increase with increasing values of Gauss–Bonnet parameter and electric charge.

scholarly journals Shadow cast of noncommutative black holes in Rastall gravity

2020 ◽  
Vol 35 (20) ◽  
pp. 2050163 ◽  
Author(s):  
Ali Övgün ◽  
İzzet Sakallı ◽  
Joel Saavedra ◽  
Carlos Leiva
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Emission Rate ◽  
Model Parameters ◽  
Spherically Symmetric ◽  
Image Model ◽  
Schwarzschild Black Hole ◽  
Physical Validity ◽  
Shadow Cast ◽  
Noncommutative Parameter

We study the shadow and energy emission rate of a spherically symmetric noncommutative black hole in Rastall gravity. Depending on the model parameters, the noncommutative black hole can reduce to the Schwarzschild black hole. Since the nonvanishing noncommutative parameter affects the formation of event horizon, the visibility of the resulting shadow depends on the noncommutative parameter in Rastall gravity. The obtained sectional shadows respect the unstable circular orbit condition, which is crucial for physical validity of the black hole image model.

scholarly journals REGULAR BLACK HOLES IN AN ASYMPTOTICALLY DE SITTER UNIVERSE

2008 ◽  
Vol 23 (40) ◽  
pp. 3377-3392 ◽  
Author(s):  
JERZY MATYJASEK ◽  
DARIUSZ TRYNIECKI ◽  
MARIUSZ KLIMEK
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Nonlinear Electrodynamics ◽  
Spherically Symmetric ◽  
De Sitter ◽  
Coupled Equations ◽  
Sitter Universe ◽  
De Sitter Universe ◽  
Horizon Geometry ◽  
Interesting Solution

A regular solution of the system of coupled equations of the nonlinear electrodynamics and gravity describing static and spherically-symmetric black holes in an asymptotically de Sitter universe is constructed and analyzed. Special emphasis is put on the degenerate configurations (when at least two horizons coincide) and their near horizon geometry. It is explicitly demonstrated that approximating the metric potentials in the region between the horizons by simple functions and making use of a limiting procedure one obtains the solutions constructed from maximally symmetric subspaces with different absolute values of radii. Topologically they are AdS2×S2 for the cold black hole, dS2×S2 when the event and cosmological horizon coincide, and the Plebański–Hacyan solution for the ultraextremal black hole. A physically interesting solution describing the lukewarm black holes is briefly analyzed.

scholarly journals Testing Generalized Einstein-Cartan-Kibble-Sciama Gravity Using Weak Deflection Angle and Shadow Cast

2020 ◽  
Author(s):  
Ali Övgün ◽  
İzzet Sakallı
Keyword(s):  
Black Hole ◽  
Gravitational Lensing ◽  
Symmetric Solution ◽  
Deflection Angle ◽  
Spherically Symmetric ◽  
Plasma Medium ◽  
Asymptotically Flat ◽  
Spherically Symmetric Solution ◽  
Shadow Cast ◽  
Bonnet Theorem

In this paper, we use a new asymptotically flat and spherically symmetric solution in the generalized Einstein-Cartan-Kibble-Sciama (ECKS) theory of gravity to study the weak gravitational lensing and its shadow cast. To this end, we first compute the weak deflection angle of generalized ECKS black hole using the Gauss–Bonnet theorem in plasma medium and in vacuum. Next by using the Newman-Janis algorithm without complexification, we derive the rotating generalized ECKS black hole and in the sequel study its shadow. Then, we discuss the effect of the ECKS parameter on the shadow of the black hole and weak deflection angle. In short, the goal of this paper is to give contribution to the ECKS theory and look for evidences to understand how the ECKS parameter effects the gravitational lensing.

scholarly journals Constructing Higher-Dimensional Exact Black Holes in Einstein-Maxwell-Scalar Theory

Universe ◽  
2020 ◽  
Vol 6 (9) ◽  
pp. 148
Author(s):  
Jianhui Qiu ◽  
Changjun Gao
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Black Hole Thermodynamics ◽  
Spherically Symmetric ◽  
Dilaton Gravity ◽  
Scalar Theory ◽  
First Law Of Thermodynamics ◽  
Higher Dimensional

We construct higher-dimensional and exact black holes in Einstein-Maxwell-scalar theory. The strategy we adopted is to extend the known, static and spherically symmetric black holes in the Einstein-Maxwell dilaton gravity and Einstein-Maxwell-scalar theory. Then we investigate the black hole thermodynamics. Concretely, the generalized Smarr formula and the first law of thermodynamics are derived.

scholarly journals Black hole thermodynamics and heat engines in conformal gravity

2017 ◽  
Vol 26 (13) ◽  
pp. 1750151 ◽  
Author(s):  
Hao Xu ◽  
Yuan Sun ◽  
Liu Zhao
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Black Hole Thermodynamics ◽  
Spherically Symmetric ◽  
Conformal Gravity ◽  
Extended Phase ◽  
Heat Engines ◽  
Equation Of States ◽  
Symmetric Black Hole ◽  
Black Hole Solutions

The extended phase-space thermodynamics and heat engines for static spherically symmetric black hole solutions of four-dimensional conformal gravity are studied in detail. It is argued that the equation of states (EOS) for such black holes is always branched, any continuous thermodynamical process cannot drive the system from one branch of the EOS into another branch. Meanwhile, the thermodynamical volume is bounded from above, making the black holes always super-entropic in one branch and may also be super-entropic in another branch in certain range of the temperature. The Carnot and Stirling heat engines associated to such black holes are shown to be distinct from each other. For rectangular heat engines, the efficiency always approaches zero when the rectangle becomes extremely narrow, and given the highest and lowest working temperatures fixed, there is always a maximum for the efficiency of such engines.

scholarly journals Scalar Perturbations of Black Holes in the f(R)=R−2αR Model

Universe ◽  
2022 ◽  
Vol 8 (1) ◽  
pp. 47
Author(s):  
Ping Li ◽  
Rui Jiang ◽  
Jian Lv ◽  
Xianghua Zhai
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Scalar Field ◽  
Critical Frequency ◽  
Amplification Factor ◽  
Quasinormal Modes ◽  
Spherically Symmetric ◽  
Third Order ◽  
Charged Scalar ◽  
The Time Domain

In this paper, we study the perturbations of the charged static spherically symmetric black holes in the f(R)=R−2αR model by a scalar field. We analyze the quasinormal modes spectrum, superradiant modes, and superradiant instability of the black holes. The frequency of the quasinormal modes is calculated in the frequency domain by the third-order WKB method, and in the time domain by the finite difference method. The results by the two methods are consistent and show that the black hole stabilizes quicker for larger α satisfying the horizon condition. We then analyze the superradiant modes when the massive charged scalar field is scattered by the black hole. The frequency of the superradiant wave satisfies ω∈(μ2,ωc), where μ is the mass of the scalar field, and ωc is the critical frequency of the superradiance. The amplification factor is also calculated by numerical method. Furthermore, the superradiant instability of the black hole is studied analytically, and the results show that there is no superradiant instability for such a system.

scholarly journals 4d Einstein-Gauss-Bonnet Gravity With Nonlinear Electrodynamics: Entropy, Energy Emission, Quasinormal Modes and Deflection Angle

2021 ◽  
Author(s):  
Sergey Il'ich Kruglov
Keyword(s):  
Black Holes ◽  
Deflection Angle ◽  
Quasinormal Modes ◽  
Einstein Equations ◽  
Nonlinear Electrodynamics ◽  
Energy Conditions ◽  
Model Parameters ◽  
Logarithmic Correction ◽  
Bonnet Gravity ◽  
Energy Emission

The logarithmic correction to Bekenshtein-Hawking entropy in the framework of 4D Einstein$-$Gauss$-$Bonnet gravity coupled with nonlinear electrodynamics is obtained. We explore the black hole solution with the spherically symmetric metric. The logarithmic term in the entropy has a structure similar to the entropy correction in the semi-classical Einstein equations which mimics the quantum correction to the area low. The energy emission rate of black holes and energy conditions are studied. Quasinormal modes of black holes are investigated. The gravitational lensing of light around BHs was investigated. We calculated the deflection angle for some model parameters.

scholarly journals SPHERICALLY SYMMETRIC TRAPPING HORIZONS, THE MISNER–SHARP MASS AND BLACK HOLE EVAPORATION

2009 ◽  
Vol 24 (28n29) ◽  
pp. 5261-5285 ◽  
Author(s):  
ALEX B. NIELSEN ◽  
DONG-HAN YEOM
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Causal Structure ◽  
Information Loss ◽  
Black Hole Thermodynamics ◽  
Spherically Symmetric ◽  
Mixed States ◽  
Unitary Evolution ◽  
Event Horizons ◽  
Trapping Horizons

We discuss some of the issues relating to information loss and black hole thermodynamics in the light of recent work on local black hole horizons. Understood in terms of pure states evolving into mixed states, the possibility of information loss in black holes is closely related to the global causal structure of space–time, as is the existence of event horizons. However, black holes need not be defined by event horizons, and in fact we argue that in order to have a fully unitary evolution for black holes, they should be defined in terms of something else, such as a trapping horizon. The Misner–Sharp mass in spherical symmetry shows very simply how trapping horizons can give rise to black hole thermodynamics, Hawking radiation and singularities. We show how the Misner–Sharp mass can also be used to give insights into the process of collapse and evaporation of locally defined black holes.

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