scholarly journals A note on Reissner–Nordström black holes in the inverse electrodynamics model

2021 ◽  
pp. 2150155
Author(s):  
S. Habib Mazharimousavi
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
General Class ◽  
Black Hole Solution ◽  
Energy Momentum Tensor ◽  
Momentum Tensor ◽  
Nonlinear Electrodynamics ◽  
Nonlinear Electrodynamic ◽  
Electric And Magnetic Fields

Recently, the inverse electrodynamics model (IEM) was introduced and applied to find Reissner–Nordström black holes in the context of the general relativity coupled minimally with the nonlinear electrodynamics. The solution consists of both electric and magnetic fields as of the dyonic solutions. Here, in this note, we show that the IEM model belongs to a more general class of the nonlinear electrodynamics with [Formula: see text]. Here, [Formula: see text] is the energy momentum tensor of the nonlinear electrodynamic Lagrangian. Naturally, such a dyonic RN black hole solution is the solution for this general class.

scholarly journals A regular scale-dependent black hole solution

2018 ◽  
Vol 27 (03) ◽  
pp. 1850032 ◽  
Author(s):  
Ernesto Contreras ◽  
Ángel Rincón ◽  
Benjamin Koch ◽  
Pedro Bargueño
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Black Hole Solution ◽  
Energy Momentum Tensor ◽  
Energy Condition ◽  
Momentum Tensor ◽  
Scale Dependence ◽  
Weak Energy Condition ◽  
Effective Energy ◽  
Regular Black Hole

In this work, we present a regular black hole solution, in the context of scale-dependent General Relativity, satisfying the weak energy condition. The source of this solution is an anisotropic effective energy–momentum tensor which appears when the scale dependence of the theory is turned-on. In this sense, the solution can be considered as a semiclassical extension of the Schwarzschild one.

scholarly journals A Smarr formula for charged black holes in nonlinear electrodynamics

2017 ◽  
Vol 32 (39) ◽  
pp. 1750219 ◽  
Author(s):  
Leonardo Balart ◽  
Sharmanthie Fernando
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
General Formula ◽  
Energy Momentum Tensor ◽  
Momentum Tensor ◽  
Nonlinear Electrodynamics ◽  
Spherically Symmetric ◽  
Charged Black Holes ◽  
Electrically Charged ◽  
Black Hole Solutions

It is well known that the Smarr formula does not hold for black holes in nonlinear electrodynamics. The main reason for this is the fact that the trace of the energy–momentum tensor for nonlinear electrodynamics does not vanish as it is for Maxwell’s electrodynamics. Starting from the Komar integral, we derived a new Smarr-type formula for spherically symmetric static electrically charged black hole solutions in nonlinear electrodynamics. We show that this general formula is in agreement with some that are obtained for black hole solutions with nonlinear electrodynamics.

scholarly journals The thermodynamic theory of black holes

1977 ◽  
Vol 353 (1675) ◽  
pp. 499-521 ◽  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Energy Momentum Tensor ◽  
Heat Bath ◽  
Naked Singularity ◽  
Momentum Tensor ◽  
Thermodynamic Theory ◽  
Model Systems ◽  
Quantum Energy ◽  
Third Law Of Thermodynamics

The thermodynamic theory underlying black hole processes is developed in detail and applied to model systems. I t is found that Kerr-Newman black holes undergo a phase transition at a = 0.68 M or Q = 0.86 M , where the heat capacity has an infinite discontinuity. Above the transition values the specific heat is positive, permitting isothermal equilibrium with a surrounding heat bath. Simple processes and stability criteria for various black hole situations are investigated. The limits for entropieally favoured black hole formation are found. The Nernst conditions for the third law of thermodynamics are not satisfied fully for black holes. There is no obvious thermodynamic reason why a black hole may not be cooled down below absolute zero and converted into a naked singularity. Quantum energy-momentum tensor calculations for uncharged black holes are extended to the Reissner-Nordstrom case, and found to be fully consistent with the thermodynamic picture for Q < M . For Q > M the model predicts that ‘naked’ collapse also produces radiation, with such intensity that the collapsing matter is entirely evaporated away before a naked singularity can form.

scholarly journals Constructing black hole solutions in supergravity theories

2019 ◽  
Vol 34 (35) ◽  
pp. 1930017 ◽  
Author(s):  
Antonio Gallerati
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Supergravity Models ◽  
Detailed Analysis ◽  
Black Hole Solution ◽  
Explicit Construction ◽  
General Introduction ◽  
Supersymmetric Theories ◽  
Black Hole Solutions

We perform a detailed analysis of black hole solutions in supergravity models. After a general introduction on black holes in general relativity and supersymmetric theories, we provide a detailed description of ungauged extended supergravities and their dualities. Therefore, we analyze the general form of black hole configurations for these models, their near-horizon behavior and characteristic of the solution. An explicit construction of a black hole solution with its physical implications is given for the STU-model. The second part of this review is dedicated to gauged supergravity theories. We describe a step-by-step gauging procedure involving the embedding tensor formalism to be used to obtain a gauged model starting from an ungauged one. Finally, we analyze general black hole solutions in gauged models, providing an explicit example for the [Formula: see text], [Formula: see text] case. A brief review on special geometry is also provided, with explicit results and relations for supersymmetric black hole solutions.

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.

scholarly journals Fuzzy dark matter black holes and droplets

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
D. Batic ◽  
D. Asem Abuhejleh ◽  
M. Nowakowski
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Black Hole Solution ◽  
Mass Parameter ◽  
Radial Pressure ◽  
Momentum Tensor ◽  
Anisotropic Fluid ◽  
De Sitter ◽  
Hole Model

AbstractWe consider the possibility of having Dark Matter (DM) black holes motivated by the Einasto density profile. This generalizes both the noncommutative mini black hole model and allows DM to enter as the matter constituent which makes up the black hole. We show that it is possible to construct a black hole solution for each value of the Einasto index and for different values of the mass parameter, provided that the we work with the energy–momentum tensor of an anisotropic fluid. In particular, we achieve that by first considering the equation of state (EOS) $$p_r=-\rho $$ p r = - ρ . It turns out that the corresponding black hole solution exhibits a horizon structure similar to that of a Reissner–Nordström black hole and the central singularity is replaced by a regular de Sitter core. We also show that if the previous EOS is replaced by a nonlocal one, it is possible to construct a self-gravitating fuzzy DM droplet but also in this case, the radial pressure is negative. Finally, we contemplate scenarios of different dark matter black holes with moderate mass values which could have formed in galaxies. In particular, we probe the possibility whether such black holes could also be the central galactic objects.

scholarly journals The shadow of M87∗ black hole within rational nonlinear electrodynamics

2020 ◽  
Vol 35 (35) ◽  
pp. 2050291
Author(s):  
S. I. Kruglov
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Event Horizon ◽  
Magnetic Charge ◽  
Nonlinear Electrodynamics ◽  
Black Hole Mass

We consider rational nonlinear electrodynamics with the Lagrangian [Formula: see text] ([Formula: see text] is the Lorentz invariant), proposed in Ref. 63, coupled to General Relativity. The effective geometry induced by nonlinear electrodynamics corrections are found. We determine shadow’s size of regular non-rotating magnetic black holes and compare them with the shadow size of the super-massive M87[Formula: see text] black hole imaged by the Event Horizon Telescope collaboration. Assuming that the black hole mass has a pure electromagnetic nature, we obtain the black hole magnetic charge. The size of the shadow obtained is very close to the shadow size of non-regular neutral Schwarzschild black holes. As a result, we can interpret the super-massive M87[Formula: see text] black hole as a regular (without singularities) magnetized black hole.

scholarly journals The Shadow of M87* Black Hole within Rational Nonlinear Electrodynamics

2020 ◽  
Author(s):  
Sergey Kruglov
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Event Horizon ◽  
Magnetic Charge ◽  
Nonlinear Electrodynamics

We consider rational nonlinear electrodynamics coupled to General Relativity. The effective geometry induced by nonlinear electrodynamics corrections are found. We determine shadows of regular non-rotating magnetic black holes and compare them with the shadow of the super-massive M87* black hole imaged by the Event Horizon Telescope collaboration. This allows us to obtain the black hole magnetic charge. The size of the shadow is very close to the shadow of non-regular neutral Schwarzschild black holes. As a result, we can interpret the super-massive M87* black hole as a regular (without singularities) magnetized black hole.

scholarly journals ENERGY CONTENTS OF A CLASS OF REGULAR BLACK HOLE SOLUTIONS IN TELEPARALLEL GRAVITY

2010 ◽  
Vol 25 (38) ◽  
pp. 3241-3250 ◽  
Author(s):  
M. SHARIF ◽  
ABDUL JAWAD
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Teleparallel Gravity ◽  
Nonlinear Electrodynamics ◽  
Hamiltonian Approach ◽  
Regular Black Hole ◽  
Nonlinear Source ◽  
Teleparallel Theory ◽  
Black Hole Solutions

In this paper, we discuss the energy–momentum problem in the realm of teleparallel gravity. The energy–momentum distribution for a class of regular black holes coupled with a nonlinear electrodynamics source is investigated by using Hamiltonian approach of teleparallel theory. The generalized regular black hole contains two specific parameters α and β (a sort of dipole and quadrupole of nonlinear source) on which the energy distribution depends. It is interesting to mention here that our results exactly coincide with different energy–momentum prescriptions in general relativity.

scholarly journals On a Model of Magnetically Charged Black Hole with Nonlinear Electrodynamics

Universe ◽  
2018 ◽  
Vol 4 (5) ◽  
pp. 66 ◽  
Author(s):  
Sergey Kruglov
Keyword(s):  
Phase Transition ◽  
Black Holes ◽  
Heat Capacity ◽  
General Relativity ◽  
Black Hole ◽  
Order Phase Transition ◽  
Nonlinear Electrodynamics ◽  
Magnetic Mass ◽  
Metric Function ◽  
Second Order Phase Transition

The Bronnikov model of nonlinear electrodynamics is investigated in general relativity. The magnetic black hole is considered and we obtain a solution giving corrections to the Reissner-Nordström solution. In this model spacetime at r → ∞ becomes Minkowski’s spacetime. We calculate the magnetic mass of the black hole and the metric function. At some parameters of the model there can be one, two or no horizons. The Hawking temperature and the heat capacity of black holes are calculated. We show that a second-order phase transition takes place and black holes are thermodynamically stable at some range of parameters.

Sign in / Sign up

Export Citation Format

Share Document