Effects Of Nonlinear Electrodynamics Research Articles

An overview of light ray deflection calculation by magnetars in nonlinear electrodynamics

Due to the lack of experimental confirmation of the effects of nonlinear electrodynamics (NED) of vacuum on the electromagnetic wave, it remains the most pressing issue. One of the most optimal media for studying these effects, occurring in astrophysics, are magnetars. Various methods of studying the bending of a wave passing through the magnetospheres of magnetars play a key role in a deeper understanding of vacuum NED. This article reviews modern methods for determining the angle of bending of the electromagnetic wave under the effect of NED of vacuum and gravity, with special attention paid to NED of vacuum in intense electromagnetic fields, which is a characteristic feature of magnetars. The article discusses various methods and techniques used to measure these angles, as well as their potential astrophysical applications.

Quantum refraction effects in pulsar emission

ABSTRACT Highly magnetized neutron stars exhibit the vacuum non-linear electrodynamics effects, which can be well-described using the one-loop effective action for quantum electrodynamics. In this context, we study the propagation and polarization of pulsar radiation, based on the post-Maxwellian Lagrangian from the Heisenberg–Euler–Schwinger action. Given the refractive index obtained from this Lagrangian, we determine the leading-order corrections to both the propagation and polarization vectors due to quantum refraction via perturbation analysis. In addition, the effects on the orthogonality between the propagation and polarization vectors and the Faraday rotation angle, all due to quantum refraction are investigated. Furthermore, from the dual refractive index and the associated polarization modes, we discuss quantum birefringence, with the optical phenomenology analogous to its classical counterpart.

Thermodynamics under the impact of thermal fluctuations and quasi-normal modes of Euler-Heisenberg AdS BH in the framework of NLED

We study the impact of thermal fluctuations on the thermodynamics, quasi-normal modes, and phase transitions of an anti-de Sitter Euler-Heisenberg black hole (BH) with a nonlinear electrodynamic field. An anti-de Sitter Euler-Heisenberg BH with a nonlinear electrodynamic field is composed of four parameters: the mass, electric charge, cosmological constant, and Euler-Heisenberg parameter. We calculate thermodynamic variables such as Hawking temperature, entropy, volume, and specific heat, which comply with the first law of thermodynamics. First, we use this BH to determine the thermodynamics and thermal fluctuations with the Euler-Heisenberg parameter to distinguish their effect on uncorrected and corrected thermodynamical quantities. We derive the expression for corrected entropy to study the impact of thermal fluctuation with simple logarithmic corrections on unmodified thermodynamical potentials, including Helmholtz energy, pressure, Gibbs free energy, and enthalpy. The Euler-Heisenberg parameter improves BH stability at large radii. Second, we analyze the local stability of the proposed BH, and the phase shifts of the BH are also investigated using temperature and specific heat. When there is a decrease in charge and an increase in and α, the temperature shifts from an unstable region to a stable one. Similarly, increases in local stability are observed with each of these parameters. Third, we use null geodesics to deal with the effects of nonlinear electrodynamics on the quasi-normal modes of the Euler-Heisenberg anti-de Sitter BH. The null geodesics provide the angular velocity and Lyapunov exponent of the photon sphere, which are the same as the real and imaginary parts of the quasi-normal modes in the eikonal limit.

On heat properties of charged AdS black holes in Gauss-Bonnet gravity coupled with nonlinear electrodynamics

We investigate the heat properties of charged AdS black holes in the Gauss-Bonnet gravity coupled with nonlinear electrodynamics. We consider the thermodynamics of black holes from the perspective of heat capacity and show that the nonlinear electrodynamics can be helpful to improve the thermodynamic stability of black holes. We perform a two-dimensional description in order to reproduce the Hawking temperature, which confirms that the Hawking temperature has an intrinsic topological nature and holds for a higher dimensional spherically symmetric spacetime. We also analyze the Maxwell equal area law and coexistence curve, and find the existence of van der Waals-like phase transitions based on critical exponents. Moreover, we deal with a charged AdS black hole in the Gauss-Bonnet gravity coupled with nonlinear electrodynamics as a working material to study holographic heat engines and obtain an exact expression for the efficiency of a rectangular engine cycle. We then discuss the effects of nonlinear electrodynamics and Gauss-Bonnet couplings on the rectangular engine cycle and compare the efficiency of this cycle with that of the Carnot cycle.

Shadow thermodynamics of AdS black hole with the nonlinear electrodynamics term

We creatively employ the shadow radius to study the thermodynamics of a charged AdS black hole with a nonlinear electrodynamics (NLED) term. First, the connection between the shadow radius and event horizon is constructed with the aid of the geodesic analysis. It turns out that the black hole shadow radius shows a positive correlation as a function of the event horizon radius. Then in the shadow context, we find that the black hole temperature and heat capacity can be presented by the shadow radius. Further analysis shows that the shadow radius can work similarly to the event horizon in revealing black hole phase transition process. In this sense, we construct the thermal profile of the charged AdS black hole with inclusion of the NLED effect. In the P < P c case, it is found that the N-type trend of the temperature given by the shadow radius is always consistent with that obtained by using the event horizon. Thus, we can conclude for the charged AdS black hole that the phase transition process can be intuitively presented as the thermal profile in the shadow context. Finally, the effects of NLED are carefully analyzed.

Weak lensing, Hawking radiation and greybody factor bound by a charged black holes with non-linear electrodynamics corrections

In this paper, we study gravitational lensing in the weak field limits and the shadow by charged black holes in non-linear electrodynamics corrections. To find the deflection angle in vacuum (non-plasma) up to the leading order terms, we compute the optical Gaussian curvature from optical metric and utilize the Gauss–Bonnet theorem by applying Gibbons and Werner’s technique. Also, we derive the bending angle in plasma and dark matter mediums and observe that the bending angle increases by increasing the effects of these mediums. Further, in vacuum and plasma mediums, we investigate the graphical behavior of the bending angle with respect to the impact parameter u and notice that the bending angle exponentially decreases. Moreover, we calculate the Hawking temperature using the Gauss–Bonnet theorem and compare it with a standard method of computing the Hawking temperature. Furthermore, we investigate the bound of the greybody factor and graphically examine that bound converges to the 1. We relate our obtained results with the results of black holes given in the literature. Finally, we have considered exploring the effect of non-linear electrodynamics (NLED), plasma and dark matter on the black hole’s shadow radius to broaden the study’s scope. Results for the shadow indicate that the three parameters give different deviations to the shadow radius. Interestingly, while plasma affects both the photonsphere and shadow, dark matter only influences the shadow.

Effect of nonlinear electrodynamics on shadows of slowly rotating black holes* *Supported by the National Key R&D Program of China (2020YFC2201400)

In this study, we investigate the effect of nonlinear electrodynamics on the shadows of charged, slowly rotating black holes with the presence of a cosmological constant. Rather than the null geodesic of the background black hole spacetime, the trajectory of a photon, as a perturbation of the nonlinear electrodynamic field, is governed by an effective metric. The latter can be derived by analyzing the propagation of a discontinuity of the electromagnetic waveform. Subsequently, the image of the black hole and its shadow can be evaluated using the backward ray-tracing technique. We explore the properties of the resultant black hole shadows of two different scenarios of nonlinear electrodynamics, namely, the logarithmic and exponential forms. In particular, the effects of nonlinear electrodynamics on the optical image are investigated, as well as the image's dependence on other metric parameters, such as the black hole spin and charge. The resulting black hole image and shadow display rich features that potentially lead to observational implications.

Charged particle motion and radiation in strong electromagnetic fields

The dynamics of charged particles in electromagnetic fields is an essential component of understanding the most extreme environments in our Universe. In electromagnetic fields of sufficient magnitude, radiation emission dominates the particle motion and effects of nonlinear quantum electrodynamics (QED) are crucial, which triggers electron-positron pair cascades and counterintuitive particle-trapping phenomena. As a result of recent progress in laser technology, high-power lasers provide a platform to create and probe such fields in the laboratory. With new large-scale laser facilities on the horizon and the prospect of investigating these hitherto unexplored regimes, we review the basic physical processes of radiation reaction and QED in strong fields, how they are treated theoretically and in simulation, the new collective dynamics they unlock, recent experimental progress and plans, as well as possible applications for high-flux particle and radiation sources.

Weak deflection angle of light in two classes of black holes in nonlinear electrodynamics via Gauss–Bonnet theorem

In this paper, we study the gravitational lensing by some black hole classes within the nonlinear electrodynamics in weak field limits. First, we calculate an optical geometry of the nonlinear electrodynamics black hole and then we use the Gauss–Bonnet theorem for finding deflection angle in weak field limits. The effect of nonlinear electrodynamics on the deflection angle in leading order terms is studied. Furthermore, we discuss the effects of the plasma medium on the weak deflection angle.

The effect of nonlinear electrodynamics on Joule-Thomson expansion of a 5-dimensional charged AdS black hole in Einstein-Gauss-Bonnet gravity

We have studied in this paper the Joule-Thomson expansion of a new charged AdS black hole with a nonlinear electrodynamics in framework of Einstein-Gauss-Bonnet gravity in AdS space. We investigated effects of mass (m), electric charge (q), GB coupling constant (α) and nonlinear electrodynamics parameter (k) on Joule-Thomson expansion by depicting different graphs. The fact that inversion temperature tends to decrease by increasing k, is in contrast to the effect of electric charge. The divergent point as well as the zero point of Joule-Thomson coefficient are also discussed. Results show that, this black hole exhibits a phase transition similar to that of van der Waals system. Furthermore, the isonthalpic curve is obtained and an interesting dependence of these curves on charge and nonlinear electrodynamics parameter is revealed. In T−P graphs, the cooling region shrinks with charge, while this region expands both with mass and with nonlinear electrodynamics parameter. Our study shows that nonlinear electrodynamics parameter plays an important role in Joule Thomson expansion.

Dynamics of test particles around magnetically charged regular black holes

In this work, we have provided detailed studies of motion test neutral, photon, neutrino-like, magnetized, and magnetically charged particles around a magnetically charged regular black hole (BH) together with properties of the spacetime curvature and event horizon around the BH. In order to see differences of linear electrodynamic (LED) and nonlinear electrodynamic (NED) charge effects in these studies, we have compared all the obtained results with the results obtained in Reissner–Nordstöm (RN) BH. It has been shown that an increase of the magnetic charge causes a decrease in the curvature invariants and event horizon radius. The study of the impact parameter for photons and neutrino-like particles has shown the effect of the magnetic charge of the regular BH, stronger than the RN one. Harmonic oscillations of test particles around regular BHs are studied. As an astrophysical application of the study, we also have provided comparisons of the effects of rotating Kerr BH spin and magnetic charge of the BH on upper, [Formula: see text] and lower, [Formula: see text] frequencies of twin peak quasi-periodic oscillations (QPOs) and represented possible values of the upper and lower frequencies of the twin-peak QPOs around these BHs in various QPO models. Finally, it is shown that the effect of magnetic charge on the ISCO radius of magnetized particles becomes stronger in higher values of magnetized parameters of the magnetized particles, where the effects of RN BH and regular BH charges become distinguishable.

Nonlinear electrodynamics effects on the black hole shadow, deflection angle, quasinormal modes and greybody factors

In this paper, we discuss the effects of nonlinear electrodynamics (NED) on non-rotating black holes, parametrized by the field coupling parameter β and magnetic charge parameter P in detail. Particularly, we survey a large range of observables and physical properties of the magnetically charged black hole, including the thermodynamic properties, observational appearance, quasinormal modes and absorption cross sections. Initially, we show that the NED black hole is always surrounded by an event horizon and any magnetic charge is permissible. We then show that the black hole gets colder with increasing charge. Investigating the heat capacity, we see that the black hole is thermally stable between points of phase transition. Introducing a generalized uncertainty principle (GUP) with a quantum gravity parameter λ extends the range of the stable region, but the effect on temperature is negligible. Then we compute the deflection angle at the weak field limit, by the Gauss-Bonnet theorem and the geodesic equation, and find that even at the first order, the magnetic charge has a contribution due to the “field mass” term. Small changes of the charge contributes greatly to the paths of null geodesics due to the P 2 dependence of the horizon radius. Using a ray-tracing code, we simulate the observational appearance of a NED black hole under different emission profiles, thin disk and spherical accretion. We find that the parameter P has a very strong effect on the observed shadow radius, in agreement with the deflection angle calculations. We finally consider quasinormal modes under massless scalar perturbations of the black hole and the greybody factor. We find that the charge introduces a slight difference in the fundamental frequency of the emitted waveform. We find that the greybody factor of the NED black hole is strongly steepened by the introduction of increasing charge. To present observational constrains, we show that the magnetic charge of the M87* black hole is between 0 ≤ P ≤ 0.024 in units of M, in agreement with the idea that real astrophysical black holes are mostly neutral. We also find that LIGO/VIRGO and LISA could detect NED black hole perturbations from BHs with masses between 5 M ☉ and 8.0 · 108 M ☉. We finally show that for black holes with masses detected with LIGO so far, charged NED black holes would deviate from Schwarzschild by 5∼10 Hz in their fundamental frequencies.

Plasma scale length and quantum electrodynamics effects on particle acceleration at extreme laser plasmas

In this work, simulations of multipetawatt lasers at irradiances ${\sim }10^{23} \ \mathrm {W}\ \mathrm {cm}^{-2}$ , striking solid targets and implementing two-dimensional particle-in-cell code was used to study particle acceleration. Preformed plasma at the front surface of a solid target increases both the efficiency of particle acceleration and the reached maximum energy by the accelerated charged particles via nonlinear plasma processes. Here, we have investigated the preformed plasma scale length effects on particle acceleration in the presence and absence of nonlinear quantum electrodynamic (QED) effects, including quantum radiation reaction and multiphoton Breit–Wheeler pair production, which become important at irradiances ${\sim } 10^{23}\ \mathrm {W}\ \mathrm {cm}^{-2}$ . Our results show that QED effects help particles gain higher energies with the presence of preformed plasma. In the results for all cases, preplasma leads to more efficient laser absorption and produces more energetic charged particles, as expected. In the case where QED is included, however, physical mechanisms changed and generated secondary particles ( $\gamma$ -rays and positrons) reversing this trend. That is, the hot electrons cool down due to QED effects, while ions gain more energy due to different acceleration methods. It is found that more energetic $\gamma$ -rays and positrons are created with increasing scale length due to high laser conversion efficiency ( ${\sim }$ 24 % for $\gamma$ -rays and $\sim$ 4 % for positrons at $L = 7\ \mathrm {\mu }\textrm {m}$ scale length), which affects the ion and electron acceleration mechanisms. It is also observed that the QED effect reduces the collimation of angular distribution of accelerated ions because the dominant ion acceleration mechanism is changing when QED is involved in the process.

Effects of non-linear electrodynamics on thermodynamics of charged black hole

This paper investigates thermodynamics, quasi-normal modes, thermal fluctuations and phase transitions of Reissner–Nordström black hole with the effects of non-linear electrodynamics. We first compute the expressions for Hawking temperature, entropy and heat capacity of this black hole and then obtain a relation between Davies’s point and quasi-normal modes with non-linear electrodynamics. We also observe the effects of logarithmic corrections on uncorrected thermodynamic quantities such as entropy, Hawking temperature, Helmholtz free energy, internal energy, Gibbs free energy, enthalpy and heat capacity. It is found that presence of non-linear electrodynamic parameter induces more instability in black holes of large radii. Finally, we analyze the phase transitions of Hawking temperature as well as heat capacity in terms of entropy for different values of charge (q), horizon radius (r+) and coupling parameter (α). We obtain that Hawking temperature changes its phase from positive to negative for increasing values of q and r+ while it shows opposite trend for higher values of α. The heat capacity changes its phase from negative to positive for large values of charge, horizon radius and coupling parameter.

Thermodynamic instability of 3D Einstein-Born-Infeld AdS black holes * *Supported in part by the National Natural Science Foundation of China (11005016, 11875196, 11375121)

Super-entropic black holes possess finite-area but noncompact event horizons and violate the reverse isoperimetric inequality. It has been conjectured that such black holes always have negative specific heat at constant volume or negative specific heat at constant pressure whenever , making them unstable in extended thermodynamics. In this paper, we describe a test of this instability conjecture with a family of nonlinear electrodynamic black holes, namely 3D Einstein-Born-Infeld (EBI) AdS black holes. Our results show that when nonlinear electrodynamics effects are weak, the instability conjecture is valid. However, the conjecture can be violated in some parameter region when nonlinear electrodynamics effects are strong enough. This observation thus provides a counter example to the instability conjecture, which suggests that super-entropic black holes may be thermodynamically stable.

Test particle orbits around regular black holes in general relativity combined with nonlinear electrodynamics

We provide detailed analysis of the curvature structure of the spacetime around regular black holes (RBHs) governed by general relativity (GR) combined with nonlinear electrodynamics (NED), characterized by electric charge $Q$, and degree of nonlinearity $n$. We consider special class of the backgrounds introduced by Toshmatov et al. [Phys. Rev. D 98, 028501 (2018)] that have proper Maxwell weak-field limit of the NED sector. We also study the motion of uncharged and charged particles in the RBH background. We determine shadows of such black holes (BHs) using the effective geometry governing motion of photons in the background of NED RBHs. The analysis of circular motion enables to determine innermost stable circular orbits (ISCO) and marginally bound orbits (MBO). We show that the radius of ISCO and MBO for neutral particles decreases as the parameters of the RBH $Q$ and $n$ increase for the fixed value of the BH mass. We demonstrate that for the electrically charged particles properties of the circular orbits strongly depend on their Coulomb interaction with the RBH charge. The dependence of the ISCO radius on the particle specific charge $q$ and the RBH parameters is rather complex, but for the attractive Coulomb interaction there is a general feature (independent of $n$) giving a limiting value of the intensity of this interaction $q{Q}_{\mathrm{max}}$ behind which no stable circular orbits are allowed around the RBH. Comparison of the RBH with Reissner-Nordstr\"om black holes (RNBH) shows that for the same electric charges of these backgrounds the location of the relevant orbits is at substantially smaller radii for the RBH, demonstrating thus a strong influence of the NED effects. The analysis of ISCO radius of test particles has shown that the charge of RBH $Q$ can mimic the rotation parameter of Kerr BH up to the value $a=0.8M$. We have also shown that the RN BH charge can mimic the rotation parameter up to $a=0.5M$ and the RBH charge up to $Q=0.2M$. Applications from observational data to the parameters of the supermassive black holes (SMBHs) at the galactic center Messier 87 (M87) and Milky Way so called Sagittarius ${\mathrm{A}}^{*}$ (${\mathrm{Sgr}\text{ }A}^{*}$) give the mimic value for the RBH charge parameter for the rotation parameter of M87 to be ${10}^{3}Q\ensuremath{\approx}277.5{6}_{\ensuremath{-}1.26}^{+3.82}$, while for ${\mathrm{Sgr}\text{ }A}^{*}$ there is ${10}^{3}Q\ensuremath{\approx}187.3{3}_{\ensuremath{-}26.4}^{+27.6}$. Moreover, it is shown that the RN BH charge cannot mimic the rotation parameter of the SMBH M87, however, it can mimic the spin parameter of ${\mathrm{Sgr}\text{ }A}^{*}$ at ${10}^{3}{Q}_{\mathrm{RN}}/M=828.7{1}_{\ensuremath{-}60.94}^{+70.58}$.

Effect of nonlinear electrodynamics on the weak field deflection angle by a black hole

In this work, we investigate the weak deflection angle of light from exact black hole within the non-linear electrodynamics. First we calculate the Gaussian optical curvature using the optical spacetime geometry. With the help of modern geometrical way popularized by Gibbons and Werner, we examine the deflection angle of light from exact black hole. For this desire, we determine the optical Gaussian curvature and execute the Gauss-Bonnet theorem on optical metric and calculate the leading terms of deflection angle in the weak limit approximation. Furthermore, we likewise study the plasma medium's effect on weak gravitational lensing by exact black hole. Hence we expose the effect of the non-linear electrodynamics on the deflection angle in the weak gravitational field.

Nonlinear electrodynamics at cylindrical “cumulation” fronts

Converging cylindrical electromagnetic fields in vacuum have been shown (Zababakhin and Nechaev Sov Phys JETP 6:345, 1958) to exhibit amplitude “cumulation”. It was found that the amplitude of self-similar waves increases without bounds at finite distances from the axis on the front of the fields reflected from the cylindrical axis. In the present paper, we propose to exploit this cylindrical cumulation process as a possible new path towards the generation of ultra-strong electromagnetic fields where nonlinear quantum electrodynamics (QED) effects come into play. We show that these effects, as described in the long wave-length limit within the framework of the Euler Heisenberg Lagrangian, induce a radius-dependent reduction of the propagation speed of the cumulation front. Furthermore, we compute the $$e^+{-}e^-$$ pair production rate at the cumulation front and show that the total number of pairs that are generated scales as the sixth power of the field amplitude.

Rotating black string in Born–Infeld gravity’s rainbow

Compact objects endowed with rotation and charge are interesting both from physical and mathematical points of view. Motivated by the recent interesting consequences of gravity’s rainbow, in this paper we introduce energy-dependent asymptotically anti-de Sitter black string solutions of Einstein–Born–Infeld gravity. We report the geometric properties of the solutions and generalize them to rotating black string solutions through an improper local transformation. We calculate the conserved and thermodynamic quantities of rotating black strings and examine the validity of the first law of thermodynamics. In addition, the effects of both rainbow functions and nonlinear electrodynamics on the thermodynamic behavior of the solutions will be studied. Finally, we investigate the thermal stability of the solutions using different methods.

Generic Regular Black Holes Related to Nonlinear Electrodynamics with Maxwellian Weak-field Limit: Shadows and Images of Keplerian Disks

Abstract We study optical phenomena in generic regular, magnetically charged, spherically symmetric black hole spacetimes arising from coupling of the Einstein gravity and nonlinear electrodynamics (NED) with the Maxwellian weak-field limit, where photons follow null geodesics of an effective geometry, directly reflecting the electromagnetic nonlinearity. We compare the motion of photons with that of massless neutrinos, which are not affected directly by nonlinearities of the non-Maxwellian electromagnetic field and follow null geodesics of the background spacetime. We determine shadows of such black holes, compare the time delays of photons and neutrinos moving in their field, and construct images of the Keplerian disks. We demonstrate that in the case of the “Maxwellian” NED black holes the optical phenomena give relevant signatures of the NED effects detectable by GRAVITY or the Event Horizon Telescope, but they are not strong enough to be excluded by recent observations as in the case of regular Bardeen black holes.