Model Of Nonlinear Electrodynamics Research Articles

Non-Singular Model of Magnetized Black Hole Based on Nonlinear Electrodynamics

A new modified Hayward metric of magnetically charged non-singular black hole spacetime in the framework of nonlinear electrodynamics is constructed. When the fundamental length introduced, characterising quantum gravity effects, vanishes, one comes to the general relativity coupled with the Bronnikov model of nonlinear electrodynamics. The metric can have one (an extreme) horizon, two horizons of black holes, or no horizons corresponding to the particle-like solution. Corrections to the Reissner–Nordström solution are found as the radius approaches infinity. As r → 0 the metric has a de Sitter core showing the absence of singularities, the asymptotic of the Ricci and Kretschmann scalars are obtained and they are finite everywhere. The thermodynamics of black holes, by calculating the Hawking temperature and the heat capacity, is studied. It is demonstrated that phase transitions take place when the Hawking temperature possesses the maximum. Black holes are thermodynamically stable at some range of parameters.

Electric Black Holes in a Model of Nonlinear Electrodynamics

AbstractThe electric counterpart of the magnetic black hole solution found in nonlinear electrodynamics (NED) is presented. The electric field emerges regular and confined whereas the spacetime which satisfies all the energy conditions is singular. Our result is in conformation with a theorem proved before about the existence of regular electric black holes. The thermal properties of the black hole including the first law, Smarr's formula, and the thermal stability are investigated. This provides a chance to compare the electric and magnetic types of black holes in a particular model of NED.

Holographic DC conductivity for backreacted nonlinear electrodynamics with momentum dissipation

We consider a holographic model with the charge current dual to a general nonlinear electrodynamics (NLED) field. Taking into account the backreaction of the NLED field on the geometry and introducing axionic scalars to generate momentum dissipation, we obtain expressions for DC conductivities with a finite magnetic field. The properties of the in-plane resistance are examined in several NLED models. For Maxwell–Chern–Simons electrodynamics, negative magneto-resistance and Mott-like behavior could appear in some parameter space region. Depending on the sign of the parameters, we expect the NLED models to mimic some type of weak or strong interactions between electrons. In the latter case, negative magneto-resistance and Mott-like behavior can be realized at low temperatures. Moreover, the Mott insulator to metal transition induced by a magnetic field is also observed at low temperatures.

Electromagnetic perturbations of black holes in general relativity coupled to nonlinear electrodynamics: Polar perturbations

The \textit{axial} electromagnetic (EM) perturbations of the black hole (BH) solutions in general relativity coupled to nonlinear electrodynamics (NED) were studied for both electrically and magnetically charged BHs, assuming that the EM perturbations do not alter the spacetime geometry in our preceding paper [Phys. Rev. D 97, 084058 (2018)]. Here, as a continuation of that work, the formalism for the \textit{polar} EM perturbations of the BHs in general relativity coupled to the NED is presented. We show that the quasinormal modes (QNMs) spectra of polar EM perturbations of the electrically and magnetically charged BHs in the NED are not isospectral, contrary to the case of the standard Reissner-Nordstr\"{o}m BHs in the classical linear electrodynamics. It is shown by the detailed study of QNMs properties in the eikonal approximation that the EM perturbations can be a powerful tool to confirm that in the NED light ray does not follow the null geodesics of the spacetime. By specifying the NED model and comparing axial and polar EM perturbations of the electrically and magnetically charged BHs, it is shown that QNM spectra of the axial EM perturbations of magnetically (electrically) charged BH and polar EM perturbations of the electrically (magnetically) charged BH are isospectral, i.e., $\omega_{mag}^{ax}\approx\omega_{el}^{pol}$ ($\omega_{mag}^{pol}\approx\omega_{el}^{ax}$).

Self-duality, helicity conservation, and normal ordering in nonlinear QED

We give a proof of the equivalence of the electric-magnetic duality on one side and helicity conservation of the tree-level amplitudes on the other side within general models of nonlinear electrodynamics. Using modified Feynman rules derived from a generalized normal ordered Lagrangian, we discuss the interrelation of the above two properties of the theory also at higher loops. As an illustration we present two explicit examples; namely we find the generalized normal ordered Lagrangian for the Born-Infeld theory and derive a semiclosed expression for the Lagrangian of the Bossard-Nicolai model (in terms of the weak field expansion with explicitly known coefficients) from its normal ordered form.

Falsifying cosmological models based on a non-linear electrodynamics

Recently, the nonlinear electrodynamics (NED) has been gaining attention to generate primordial magnetic fields in the Universe and also to resolve singularity problems. Moreover, recent works have shown the crucial role of the NED on the inflation. This paper provides a new approach based on a new model of NED as a source of gravitation to remove the cosmic singularity at the big bang and explain the cosmic acceleration during the inflation era on the background of stochastic magnetic field. Also, we found a realization of a cyclic Universe, free of initial singularity, due to the proposed NED energy density. In addition, we explore whether a NED field without or with matter can be the origin of the late-time acceleration. For this we obtain explicit equations for H(z) and perform a MCMC analysis to constrain the NED parameters by using 31 observational Hubble data (OHD) obtained from cosmic chronometers covering the redshift range 0< z < 1.97; and with the joint-light-analysis (JLA) SNIa compilation consisting in 740 data points in the range 0.01<z<1.2. All our constraints on the current magnetic field give B_{0}sim 10^{-31}mathrm {cm^{-1}}, which are larger than the upper limit 10^{-33}mathrm {cm^{-1}} by the Planck satellite implying that NED cosmologies could not be suitable to explain the Universe late-time dynamics. However, the current data is able to falsify the scenario at late times. Indeed, one is able to reconstruct the deceleration parameter q(z) using the best fit values of the parameters obtained from OHD and SNIa data sets. If the matter component is not included, the data sets predict an accelerated phase in the early Universe, but a non accelerated Universe is preferred in the current epoch. When a matter component is included in the NED cosmology, the data sets predict a q(z) dynamics similar to that of the standard model. Moreover, both cosmological data favor up to 2sigma confidence levels an accelerating expansion in the current epoch, i.e., the Universe passes of a decelerated phase to an accelerated stage at redshift sim 0.6. Therefore, although the NED cosmology with dust matter predict a value B_{0} higher than the one measured by Planck satellite, it is able to drive a late-time cosmic acceleration which is consistent with our dynamical systems analysis and it is preferred by OHD and SNIa data sets.

On a Model of Magnetically Charged Black Hole with Nonlinear Electrodynamics

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.

Magnetically charged black hole in framework of nonlinear electrodynamics model

A model of nonlinear electrodynamics is proposed and investigated in general relativity. We consider the magnetic black hole and find a regular solution which gives corrections into the Reissner–Nordström solution. At [Formula: see text] the asymptotic space–time becomes flat. The magnetic mass of the black hole is calculated and the metric function is obtained. At some values of the model parameter there can be one, two or no horizons. Thermodynamics of black holes is studied and we calculate the Hawking temperature and heat capacity of black holes. It is demonstrated that there is a phase transition of second order. At some parameters of the model black holes are thermodynamically stable.

Notes on Born–Infeld-type electrodynamics

We propose a new model of nonlinear electrodynamics (NLED) with three parameters. Born–Infeld (BI) electrodynamics and exponential electrodynamics are particular cases of this model. The phenomenon of vacuum birefringence in the external magnetic field is studied. We show that there is no singularity of the electric field at the origin of point-like charged particles. The corrections to Coulomb’s law at [Formula: see text] are obtained. We calculate the total electrostatic energy of charges, for different parameters of the model, which is finite.

Nonsingular black holes, wormholes, and de Sitter cores from anisotropic fluids

We study Born-Infeld gravity coupled to an anisotropic fluid in a static, spherically symmetric background. The free function characterizing the fluid is selected on the following grounds: i) recovery of the Reissner-Nordstr\"om solution of General Relativity at large distances, ii) fulfillment of classical energy conditions, and iii) inclusion of models of nonlinear electrodynamics as particular examples. Four branches of solutions are obtained, depending on the signs of two parameters on the gravity and matter sectors. On each branch, we discuss in detail the modifications on the innermost region of the corresponding solutions, which provides a plethora of configurations, including nonsingular black holes and naked objects, wormholes, and de Sitter cores. The regular character of these configurations is discussed according to the completeness of geodesics and the behavior of curvature scalars.

Magnetized black holes and nonlinear electrodynamics

A new model of nonlinear electrodynamics with two parameters is proposed. We study the phenomenon of vacuum birefringence, the causality and unitarity in this model. There is no singularity of the electric field in the center of pointlike charges and the total electrostatic energy is finite. We obtain corrections to the Coulomb law at [Formula: see text]. The weak, dominant and strong energy conditions are investigated. Magnetized charged black hole is considered and we evaluate the mass, metric function and their asymptotic at [Formula: see text] and [Formula: see text]. The magnetic mass of the black hole is calculated. The thermodynamic properties and thermal stability of regular black holes are discussed. We calculate the Hawking temperature of black holes and show that there are first-order and second-order phase transitions. The parameters of the model when the black hole is stable are found.

Born–Infeld-type electrodynamics and magnetic black holes

We investigate a Born–Infeld-type model of nonlinear electrodynamics, possessing three parameters, coupled with general relativity. As a particular case Born–Infeld electrodynamics is reproduced. There is no singularity of the electric field at the center of point-like charged particles and self-energy of charges is finite in this model. The magnetized black hole is studied and solutions are obtained. We find the asymptotic of the metric and mass functions at r→∞ and r→0, and corrections to the Reissner–Nordström solution. Thermodynamics of black holes is investigated. We calculate the Hawking temperature of black holes and show that black holes are stable and there are no phase transitions in the model under consideration.

Nonlinear Electrodynamics and Magnetic Black Holes

A model of nonlinear electrodynamics with two parameters, coupled with general relativity, is investigated. We study the magnetized black hole and obtain solutions. The asymptotic of the metric and mass functions at and , and corrections to the Reissner‐Nordström solution are found. We investigate thermodynamics of black holes and calculate the Hawking temperature and heat capacity of black holes. It is shown that there are phase transitions and at some parameters of the model black holes are stable.

Remarks on Heisenberg–Euler-type electrodynamics

We consider Heisenberg–Euler-type model of nonlinear electrodynamics with two parameters. Heisenberg–Euler electrodynamics is a particular case of this model. Corrections to Coulomb’s law at [Formula: see text] are obtained and energy conditions are studied. The total electrostatic energy of charged particles is finite. The charged black hole solution in the framework of nonlinear electrodynamics is investigated. We find the asymptotic of the metric and mass functions at [Formula: see text]. Corrections to the Reissner–Nordström solution are obtained.

Inflation of universe due to nonlinear electrodynamics

A model of nonlinear electrodynamics with a dimensional parameter [Formula: see text] is considered. Electromagnetic fields are the source of the gravitation field and inflation of the universe. We imply that the universe is filled by stochastic magnetic fields. It is demonstrated that after the universe inflation the universe decelerates approaching the Minkowski space–time. We evaluate the spectral index, the tensor-to-scalar ratio, and the running of the spectral index which approximately agree with the Planck and WMAP data.

Black hole as a magnetic monopole within exponential nonlinear electrodynamics

We perform the gauge covariant quantization of the exponential model of nonlinear electrodynamics. Magnetically charged black holes, in the framework of our model are considered, and the regular black hole solution is obtained in general relativity. The asymptotic black hole solution at r→∞ is found. We calculate the magnetic mass of the black hole and the metric function which are expressed via the parameter β of the model and the magnetic charge. The thermodynamic properties and thermal stability of regular black holes are analysed. We calculate the Hawking temperature of black holes and their heat capacity at the constant magnetic charge. We find a point where the temperature changes the sign that corresponds to the first-order phase transition. It is shown that at critical point, where the heat capacity diverges, there is a phase transition of the second-order. We obtain the parameters of the model when the black hole is stable.

Corrections to Reissner-Nordström black hole solution due to exponential nonlinear electrodynamics

An exponential model of nonlinear electrodynamics coupled with the gravitational field is analyzed. It was shown that weak, dominant, and strong energy conditions are satisfied. We obtain corrections to Coulomb's law at r → ∞. It was demonstrated that the electric-magnetic duality between and frames is violated. The asymptotic black hole solution at is found that contains corrections to the Reissner-Nordström solution. The electromagnetic mass of the black hole is calculated, expressed through the parameter β of the model.

Asymptotic Reissner-Nordström solution within nonlinear electrodynamics

A model of nonlinear electrodynamics coupled with the gravitational field is studied. We obtain the asymptotic black hole solutions at $r\rightarrow 0$ and $r\rightarrow \infty$. The asymptotic at $r\rightarrow 0$ is shown, and we find corrections to the Reissner-Nordstr\"om solution and Coulomb's law at $r\rightarrow\infty$. The mass of the black hole is evaluated having the electromagnetic origin. We investigate the thermodynamics of charged black holes and their thermal stability. The critical point corresponding to the second-order phase transition (where heat capacity diverges) is found. If the mass of the black hole is greater than the critical mass, the black hole becomes unstable.

Effective geometries and generalized uncertainty principle corrections to the Bekenstein-Hawking entropy

In this work we construct several black-hole metrics which are consistent with the generalized uncertainty principle logarithmic correction to the Bekenstein-Hawking entropy formula. After preserving the event horizon at the usual position, a singularity at the Planck scale is found. Finally, these geometries are shown to be realized by certain model of non-linear electrodynamics, which resembles previously studied regular black-hole solutions.

Nonlinear arcsin‐electrodynamics and asymptotic Reissner‐Nordström black holes

A model of nonlinear electrodynamics with the Lagrangian density is proposed. The scale invariance and the dual invariance of electromagnetic fields are broken in the model. In the limit one comes to Maxwell's electrodynamics and the scale and dual invariances are recovered. We investigate the effect of coupling electromagnetic fields with the gravitational field. The asymptotic black hole solution is found which is similar to the Reissner‐Nordström solution. We obtain corrections to Coulomb's law and to the Reissner‐Nordström solution in the model proposed. The existence of the regular asymptotic at was demonstrated. The mass of the black hole is calculated possessing the electromagnetic origin. It was shown that there are not superluminal fluctuations and principles of causality and unitarity take place.