The main objective of this work is the construction of regular black hole solutions in the context of the Einstein-Maxwell theory. The strategy is to match an interior regular solution to an exterior electrovacuum solution. With this purpose, we first write explicitly the Einstein field equations for the interior regular region. We take an electrically charged nonisotropic fluid, which presents spherical symmetry and a de Sitter type equation of state, where the radial pressure $p_r$ is equal to the negative of energy density $ρ$, $p_r=-ρ$. Then, two solutions for the Einstein equations are built, a regular interior solution for the region with matter satisfying a de Sitter equation of state, and an external solution for the region outside the matter, that corresponds to the Reissner-Nordström metric. To complete the solution we apply the Darmois-Israel junction conditions with a timelike thin shell at the matching surface. It is assumed that the matching surface is composed by a thin shell of matter, i.e., a surface layer in the form a perfect fluid obeying a barotropic equation of state, $\mathcal{P}=ωσ$, $P$ and $σ$ being the intrinsic pressure and energy density of the shell, respectively, and $ω$ a constant parameter. We show that there are electrically charged regular black hole solutions and other compact objects for specific choices of $ω$ and of the other parameters of the model. Some properties of the objects are investigated.
In this paper, static electrically charged black hole solutions with cosmological constant are investigated in an Einstein-Hilbert theory of gravity with additional quadratic curvature terms. Beside the analytic Schwarzschild (Anti-) de Sitter solutions, non-Schwarzschild (Anti-) de Sitter solutions are also obtained numerically by employing the shooting method. The results show that there exist two groups of asymptotically (Anti-) de Sitter spacetimes for both charged and uncharged black holes. In particular, it was found that for uncharged black holes the first group can be reduced to the Sc…
The gravitational Poynting vector provides a mechanism for the transfer of gravitational energy to a system of falling objects. In the following we will show that the gravitational poynting vector together with the electromagnetic Poynting vector provides a mechanism to explain how massive electrically charged bodies acquire kinetic energy during a free fall. We will demontrate that falling electrically charged masses violate the Galilean law of universal free fall. An experiment is suggested to confirm or not the predicted phenomena.
We find a class of electrically charged exact solutions for a toy model of metric-affine gravity. Their metric is of the Plebański-Demiański type and their nonmetricity and torsion are represented by a triplet of covectors with dilation, shear, and spin charges.
We address the question of existence of regular spherically symmetric electrically charged solutions in Nonlinear Electrodynamics coupled to General Relativity. Stress-energy tensor of the electromagnetic field has the algebraic structure $T_0^0=T_1^1$. In this case the Weak Energy Condition leads to the de Sitter asymptotic at approaching a regular center. In de Sitter center of an electrically charged NED structure, electric field, geometry and stress-energy tensor are regular without Maxwell limit which is replaced by de Sitter limit: energy density of a field is maximal and gives an effect…
We sketch the results of calculations of the quasinormal frequencies of the electrically charged dilaton black hole. At the earlier phase of evaporation (Q is less than 0.7-0.8M), the dilaton black hole "rings" with the complex frequencies which differ negligibly from those of the Reissner-Nordstrom black hole. The spectrum of the frequencies weakly depends upon the dilaton coupling.
The characteristic time of disappearance of electric field in massive electrodynamics during the capture of electric charge by black holes is calculated. It is shown that this time does not depend upon the photon mass. The electric field at large distances disappears with the speed of light.
Particle dynamics around an electrically charged Kiselev black hole embedded in quintessence
Faculty of Physics, “Alexandru Ioan Cuza” University of Iasi（雅西亚历山德鲁·约安·库扎大学物理学院）；Department of Exact and Natural Sciences, Institute of Interdisciplinary Research, “Alexandru Ioan Cuza” University of Iasi（雅西亚历山德鲁·约安·库扎大学跨学科研究所精确与自然科学系）
We present the full set of analytical solutions of the geodesic equations of charged test particles in the Reissner-Nordström space-time in terms of the Weierstraß $\wp$, $σ$ and $ζ$ elliptic functions. Based on the study of the polynomials in the $\vartheta$ and $r$ equations we characterize the motion of test particles and discuss their properties. The motion of charged test particles in the Reissner-Nordström space-time is compared with the motion of neutral test particles in the field of a gravitomagnetic monopole. Electrically or magnetically charged particles in the Reissner-Nordström sp…
In this paper, I determine the electrogravitational field produced by a charged mass point according to the Relativistic Theory of Gravitation. The Causality Principle in the Relativistic Theory of Gravitation will play a very important part in finding this field. The analytical form and the domain of definition, i.e the gravitational radius of the obtained solution, differ from that given by Einstein's General Relativity Theory.
In nonlinear electrodynamics coupled to gravity, regular spherically symmetric electrically charged solutions satisfy the weak energy condition and have obligatory de Sitter centre. By the Gürses-Gürsey algorithm they are transformed to spinning electrically charged solutions asymptotically Kerr-Newman for a distant observer. Rotation transforms de Sitter center into de Sitter vacuum surface which contains equatorial disk $r=0$ as a bridge. We present general analysis of the horizons, ergoregions and de Sitter surfaces, as well as the conditions of the existence of regular solutions to the fie…
The time-like naked singularities of the electrically and magnetically charged black hole solutions obtained in a model of nonlinear electrodynamics proposed by Kruglov is investigated within the framework of quantum mechanics. In view of quantum mechanics, the space-time is quantum regular provided that the time evolution of the test quantum wave packet uniquely propagates on an underlying background. Rigorous calculations have shown that when the singularity is probed with specific quantum wave/particle modes, the quantum wave operator turns out to be essentially self-adjoint. Thus, the time…
With motivation by holography, employing black hole entropy, two point connection function and entanglement entropy, we show that, for the higher dimensional Anti-de Sitter charged hairy black hole in the fixed charged ensemble, a Van der Waals-like phase transition can be observed. Furthermore, based on the Maxwell's equal area construction, we check numerically the equal area law for a first order phase transition in order to further characterize the Van der Waals-like phase transition.
The approximate renormalized stress-energy tensor of the quantized massive conformally coupled scalar field in the spacetime of electrically charged nonlinear black hole is constructed. It is achieved by functional differentiation of the lowest order of the DeWitt-Schwinger effective action involving coincidence limit of the Hadamard-Minakshisundaram-DeWitt-Seely coefficient $a_{3}.$ The result is compared with the analogous result derived for the Reissner-Nordström black hole. It is shown that the most important differences occur in the vicinity of the event horizon of the black hole near the…
We investigate the properties of non-rotating, electrically charged strange quark stars in four-dimensional Einstein-Maxwell theory. For quark matter we adopt the well-motivated quantum chromodynamics (QCD) equation-of-state, while for the charge density we assume it is proportional to the mass density. The system of coupled structure equations are integrated numerically, and we compute the mass, the radius as well as the total electric charge of the stars. Moreover, we perform a detailed numerical study of the effect of electric charge using the interacting quark equation-of-state. We find th…
Recently M. Kamata and T. Koikawa claimed to obtain the charged version of the spinning BTZ black hole solution by assuming an (anti-) self dual condition imposed on the orthonormal basis components of the electric and magnetic fields. We point out that the Kamata-Koikawa field is not a solution of the Einstein-Maxwell equations and we find the correct solution of the studied problem. It is shown that a duality mapping exists among spinning solutions obtained from electrostatic and magnetostatic fields with the help of the local transformation $t\longrightarrow t-ωθθ\longrightarrow θ-ωt.$
We investigate the influence of vacuum polarization of quantum massive fields on the scalar sector of quasinormal modes in spherically symmetric black holes. We consider the evolution of a massless scalar field on the spacetime corresponding to a charged semiclassical black hole, consisting of the quantum corrected geometry of a Reissner-Nordström black hole dressed by a quantum massive scalar field in the large mass limit. Using a sixth order WKB approach we find the shift in the quasinormal mode frequencies due to vacuum polarization .
In this paper we will show that using the cosmological constant as a new thermodynamical state variable, the differential and integral mass formulas of the first law of thermodynamics for asymptotic flat spacetimes can be extended to (2+1) dimensional charged BTZ black holes and charged de Sitter space.
Considering electrically charged test particles, we continue our study of the exterior dynamics of a charged Weyl black hole which has been previously investigated regarding the motion of mass-less and (neutral) massive particles. In this paper, the deflecting trajectories of charged particles are designated as being gravitationally Rutherford-scattered and detailed discussions of angular and radial particle motions are presented.
This paper aims to investigate the astrophysical applicability of the electrically and magnetically charged black hole solutions obtained in a model of nonlinear electrodynamics proposed by Kruglov (Ann. Phys. Berlin 2017, 529, 170073). Theoretical calculations of the bending angles and gravitational redshifts from the theory of general relativity are studied numerically by using the stellar data of charged compact objects and a hypothetical quark star model. Calculations have revealed that although the theoretical outcomes differ from the linear Maxwell case, the plotted bending angles coinci…
Along the last decades, several regular black hole (BH) solutions, i.e., singularity-free BHs, have been proposed and associated to nonlinear electrodynamics models minimally coupled to general relativity. Within this context, it is of interest to study how those nonlinear-electrodynamic-based regular BHs (RBHs) would interact with their astrophysical environment. We investigate the propagation of a massless test scalar field in the background of an electrically charged RBH solution, obtained by Eloy Ayón-Beato and Alberto García. Using a numerical approach, we compute the absorption cross sec…
The notion of a compact object immune to the horizon problem and comprising an anisotropic inhomogeneous fluid with a specific radial pressure behavior, i.e. the gravastar, is extended by introducing an electrically charged component. Einstein-Maxwell field equations are solved in the asymptotically de Sitter interior where a source of the electric field is coupled to the fluid energy density. Two different solutions which satisfy the dominant energy condition are given: one is the delta-shell model for which the analysis is carried out within Israel's thin shell formalism, the other approach …
In this paper we study the Hawking evaporation of masses of variable-charged Reissner-Nordstrom and Kerr-Newman, black holes embedded into the de Sitter universe by considering the charge to be function of radial coordinate of the spherically symmetric metric.
In this paper, new electrically charged asymptotically flat black hole solutions are numerically derived in the context of higher derivative gravity. These solutions can be interpreted as generalizations of two different classes of non-charged asymptotically flat spacetimes: Schwarzschild and non-Schwarzschild solutions. Extreme black hole solutions and black holes with negative mass were found.
We derive a rotating counterpart of the five-dimensional electrically charged Bardeen regular black holes spacetime by employing the Giampieri algorithm on static one. The associated nonlinear electrodynamics source is computed in order to justify the rotating solution. We thoroughly discuss the energy conditions and the other properties of the rotating spacetime. The black hole thermodynamics of the rotating spacetime is also presented. In particular, the thermodynamic quantities such as the Hawking temperature and the heat capacity are calculated and plotted to see the thermal behavior. The …
We investigate the occurrence of naked singularities in the spherically symmetric, plane symmetric and cylindrically symmetric collapse of charged null fluid in an anti-de Sitter background. The naked singularities are found to be strong in Tipler's sense and thus violate the cosmic censorship conjecture, but not hoop conjecture.
Using a general solution-generating technique for electrically charged relativistic stars with spherical symmetry, we derive a new bound on the mass-radius ratio. This compactness bound is based on the already established bounds for uncharged interior solutions and it will provide the corresponding generalizations in presence of the electric charge.
In this work we address the study of movement of charged particles in the background of charged black holes with non-trivial asymptotic behavior. We compute the exact trajectories for massive-charged particles in term of elliptic Jacobi function. Finally we obtain a detailed description of orbits for Reissner-Nordström (Anti)-de Sitter black holes in terms of charge, mass and energy of the particles.
We study the Gregory-Laflamme instability of 5D compactified, electrically charged black strings. We consider static, linear perturbations of these solutions and derive master equation for these perturbations. Using numerical analysis we search for the threshold unstable modes and derive the critical wave-length. The results are illustrated in the black string mass v.s. electric charge phase diagram. Similar diagram is constructed using global thermodynamic equilibrium argument applied to the charged string and 5D electrically charged black hole. The results derived illustrate that electric ch…
Nonlinear electrodynamic (NLED) theories are well-motivated for their extensions to classical electrodynamics in the strong field regime, and have been extensively investigated in seeking for regular black hole solutions. In this paper, we focus on two spherically symmetric and static black hole solutions based on two types of NLED models: the Euler-Heisenberg NLED model and the Bronnikov NLED model, and calculate the weak deflection angle of light by these two black holes with the help of the Gauss-Bonnet theorem. We investigate the effects of the one-loop corrections to quantum electrodynami…
We study charged-fluid toroidal structures surrounding a non-rotating charged black hole immersed in a large-scale, asymptotically uniform magnetic field. In continuation of our former study on electrically charged matter in approximation of zero conductivity, we demonstrate existence of orbiting structures in permanent rigid rotation in the equatorial plane, and charged clouds hovering near the symmetry axis. We constrain the range of parameters that allow stable configurations and derive the geometrical shape of equi-pressure surfaces. Our simplified analytical study suggests that these regi…
We perform a Hadamard point-split renormalization of the current density $j_ν$ of a charged scalar field in a Reissner-Nordström-de Sitter spacetime. We compute numerically the expectation values of the components $j_r$ and $j_t$ in the Unruh state in the exterior region and study their dependence on the field parameters and the position.
We examine the thermodynamic behaviour of four-dimensional charged and uncharged de Sitter black holes enclosed in an isothermal cavity, in the extended phase space where the cosmological constant is treated as a thermodynamic pressure. We demonstrate the presence of a novel pressure-dependent phase transition in a compact region of phase space that does not appear in asymptotically anti-de Sitter black holes, and find a highly non-linear equation of state that does not lead to the usual interpretation of a van der Waals fluid.
In the present paper we construct a new solution to the Einstein-Maxwell-dilaton gravity equations describing electrically charged dilaton black holes immersed in a strong external magnetic field and we study its properties. The black holes described by the solution are rotating but with zero total angular momentum and possess an ergoregion confined in a neighborhood of the horizon. Our results also show that the external magnetic field does not affect the black hole thermodynamics.
Regular black hole solutions are found among the Guilfoyle exact solutions. These are spherically symmetric solutions of general relativity coupled to Maxwell's electromagnetism and charged matter where the metric potentials and electromagnetic fields are related in some particularly simple form. We show that, for certain ranges of the parameters, there are objects which correspond to regular charged black holes, whose interior region is filled by an electrically charged phantom-like fluid, or, in the limiting case, a de Sitter false vacuum fluid, and whose exterior region is Reissner-Nordströ…
A regular static, spherically symmetric electrically charged black hole solution of general relativity coupled to a new theory for nonlinear electrodynamics is presented. This theory has the interesting feature that, at far distances from the black hole, in the weak field limit, the theory reduces to Maxwell Lagrangian with Heisenberg-Euler correction term of quantum electrodynamics. The singular center of the black hole is replaced by flat, de Sitter, or anti de Sitter space, if the spacetime in which the black hole is embedded is asymptotically flat, de Sitter, or anti de Sitter, respectivel…
We study the dynamics of charged, spherically symmetric dust shells in the presence of a positive cosmological constant. We find generalizations of the well-known solutions in asymptotically flat spacetime, in particular orbits into "parallel universes", but also new solutions corresponding to a "bounce" of the shell before an event horizon has formed. We also discuss "bubble" solutions, in which a charged shell and an oppositely charged singularity are spontaneously created and annihilated.
We study the decay of charged scalar and spinor fields around Reissner-Nordstrom black holes in de Sitter spacetime through calculations of quasinormal frequencies of the fields. The influence of the parameters of the black hole (charge, mass), of the decaying fields (charge, spin), and of the spacetime (cosmological constant) on the decay is analyzed. The analytic formula for calculation quasinormal frequencies for a large multipole number (eikonal approximation) is derived both for the spinor and scalar fieldss.
We investigate the properties of relativistic star spheres made of an electrically charged incompressible fluid, generalizing, thus, the Schwarzschild interior solution. The investigation is carried by integrating numerically the hydrostatic equilibrium equation, i.e., the Tolman-Oppenheimer-Volkoff (TOV) equation, with the hypothesis that the charge distribution is proportional to the energy density. We match the interior to a Reissner-Nordström exterior, and study some features of these star spheres such as the total mass $M$, the radius $R$, and the total charge $Q$. We also display the pre…
We study a charged Taub-NUT spacetime solution in the DGP brane. We show that the Reissner-Nordstrom-Taub-NUT-de Sitter solution of Einstein-Maxwell gravity solves the corresponding equations of motion, where the cosmological constant is related to the cross-over scale in the DGP model. Following the approach by Teitelboim in discussing the thermodynamics of de Sitter spacetime and the proposal by Wu et al. for a conserved charge associated to the NUT parameter, we obtained the generalized Smarr mass formula and the first law of thermodynamics of the spacetime.
It has recently been shown that the strong cosmic censorship conjecture can be violated by the massless neutral scalar field in the nearly extremal Reissner-Nordstrom-de Sitter black hole. However, the formation of such a black hole by gravitational collapse necessitates the presence of the charged sector on top of the Einstein-Maxwell system. Thus we numerically calculate the quasi-normal modes for a massless charged scalar field in the Reissner-Nordstrom-de Sitter spacetime by generalizing the characteristic formulation to the charged case. As a result, the strong cosmic censorship turns out…
We derive the equations for the odd and even parity perturbations of coupled electromagnetic and gravitational fields of a black hole with an electric charge within the context of general nonlinear electrodynamics. The Lagrangian density is a generic function of the Lorentz invariant scalar quantities of the electromagnetic fields. We include the Hodge dual of the electromagnetic field tensor and the cosmological constant in our calculations. For each type of parity, we reduce the system of Einstein field equations coupled to nonlinear electrodynamics to two coupled Schrödinger-type wave equat…
We study the stability of static, spherically symmetric, traversable wormholes with or without an electric charge, existing due to conformal continuations in a class of scalar-tensor theories with zero scalar field potential (so that Penney's or Fisher's well-known solutions hold in the Einstein conformal frame). Specific examples of such wormholes are those with nonminimally (e.g., conformally) coupled scalar fields. All boundary conditions for scalar and metric perturbations are taken into account. All such wormholes with zero or small electric charge are shown to be unstable under spherical…
We studied the instability of the regularized 4D charged Einstein-Gauss-Bonnet de-Sitter black holes under charged scalar perturbations. The unstable modes satisfy the superradiant condition, but not all modes satisfying the superradiant condition are unstable. The instability occurs when the cosmological constant is small and the black hole charge is not too large. The Gauss-Bonnet coupling constant makes the unstable black hole more unstable when both the black hole charge and cosmological constant are small, and makes the stable black hole more stable when the black hole charge is large.
We study the instability of charged anti-de Sitter black holes in four or higher-dimension under fragmentation. The instability of fragmentation breaks the black hole into two black holes. We have found that the region near extremal or massive black holes become unstable under fragmentation. These regions depend not only on the mass and charge of initial black hole but also those of the fragmented one. The instability in higher-dimension is qualitatively similar to that of four-dimension. The detailed instabilities are numerically investigated.
We study the theory of interaction between charged scalar field and Maxwell field in de Sitter background. Solving the equation of interacting fields we define the in-out fields as asymptotic free fields and construct the reduction formalism for scalar field. Then we derive the perturbation expansion of the scattering operator. The first order transition amplitudes corresponding to particle production from de Sitter vacuum and pair production in an external field are analysed. We show that all these effects are important only in strong gravitational fields and vanish in the flat limit.
The exact charged rotating solution of 2+1 Einstein-Maxwell equations with $Λ$ term is obtained and its properties outlined. It generalizes the Cataldo-Cruz-del Campo-Garc{\'ı}a relativistic charged massive black hole on the 2+1 anti-de Sitter cosmological background. We show that rotating solutions correspond to inhomogeneous field equations, thus presence of sources in 2+1 Maxwell's equations cannot be identified with existence of a charge distribution. Instead, these sources are related to the 2+1 Machian 2-form field, and the overall Lagrangian structure of the rotating system is reconstru…
In this work we investigate the presence of electrically charged structures that are localized in two and three spatial dimensions. We use the Maxwell-scalar Lagrangian to describe several systems with distinct interactions for the scalar fields. The procedure relies on finding first order differential equations that solve the equations of motion and ensure stability of the corresponding minimum energy solutions. We illustrate the many possibilities in two and in three spatial dimensions, examining different examples of electrically charged solutions that engender internal structure
We study the linear instability of the charged massless scalar perturbation in regularized 4D charged Einstein-Gauss-Bonnet-AdS black holes by exploring the quasinormal modes. We find that the linear instability is triggered by superradiance. The charged massless scalar perturbation becomes more unstable when increasing the Gauss-Bonnet coupling constant or the black hole charge. Meanwhile, decreasing} the AdS radius will make the charged massless scalar perturbation} more stable. The stable region in parameter space $(α,Q,Λ)$ is given. Moreover, we find that the charged massless scalar pertur…
We study Hawking radiation as a phenomenon of tunneling through event horizons of charged torus-like as well as dilaton black holes involving cosmological constant based on Kerner and Mann's formulation. We obtain tunneling probabilities as well as Hawking's emission temperature of outgoing charged particles by applying the semiclassical WKB approximation to the general covariant Dirac equation. The graphical behavior of Hawking temperature and horizon radius is investigated. We find results consistent with those already given in literature.
