Geodesic Study of a Charged Black Hole

The behavior of the timelike and null geodesics of charged E. Ayón-Beato and A. Garcia (ABG) black hole are investigated. For circular and radial geodesics, we investigate all the possible motions by plotting the effective potentials for different parameters. In conclusion, we have shown that there is no phenomenon of superradiance in this case.     

Spherical Photon Orbits Around a Kerr Black Hole

Two circular photon orbits are known to exist in the equatorial plane of the Kerr black hole. In this paper, we investigate so-called spherical photon orbits—orbits with constant coordinate radii that are not confined to the equatorial plane. A one-parameter class of solutions is found, which includes the circular orbits as special cases. The properties of these spherical orbits are then analyzed, with the aim of classifying them by qualitative differences in their behavior. Finally, representative orbits from each class are plotted out, including a zero-angular momentum photon orbit and one with non-fixed azimuthal direction.     

Bergmann-Thomson Energy of a Charged Rotating Black Hole

We obtain the energy distribution associated with a charged rotating (Kerr-Newman) black hole in Bergmann-Thomson formulation. We find that the energy-momentum definitions prescribed by Einstein, Landau-Lifshitz, Papapetrou, Weinberg, and Bergmann-Thomson give the same and acceptable result and also support the Cooperstock hypothesis for energy localization in general relativity. The repulsive effect due to the electric charge and rotation parameters of the metric is also reflected from the energy distribution expression.     

Chaotic Motion of a Charged Particle around a Weakly Magnetized Schwarzschild Black Hole Containing Cosmic String

We discuss the conditions where a charged particle that was originally revolving around a weakly magnetized black hole containing cosmic string in the innermost stable circular orbit will escape to infinity after it is kicked by another particle or photon. We find that the motion of the kicked particle is chaotic. The critical escape energy and velocity of the kicked charged particle with different initial radial velocities are obtained.     

Back Reaction of Charged Black Hole

The existence of the Hawking radiation of theblack hole surely affects spacetime. Here, using athermodynamic approach, to avoid the difficulty offinding the energy-momentum tensor, we obtainexpressions for the energy and entropy of theReissner–Nordstrom black hole (RNBH), and providea better way of solving the backreaction of more complexblack holes.     

Geometrothermodynamics of a Charged Black Hole of String Theory

The thermodynamics of the Gibbons–Maeda–Garfinkle–Horowitz–Strominger charged black hole from string theory is reformulated within the context of the recently developed formalism of geometrothermodynamics. The geometry of the space of equilibrium states is curved, but we show that the thermodynamic curvature does not diverge at the phase transition point expected when the black hole solution becomes a naked singularity. This provides a counterexample to the conventional notion that such a divergence signals the occurrence of a second-order phase transition.     

The Shell of Incoherent Charged Matter Falling onto a Charged Rotating Black Hole

The motion of the shell of charged testparticles falling radially from rest at infinity withzero total angular momentum onto a Kerr–Newmanblack hole is studied. The shell, initially spherical,becomes prolate along the axis of symmetry of the holeduring the fall. The shape of the shell from theviewpoint of distant observers is characterized by meansof the photons moving along geodesics of the outgoing principal null congruence. The motion of theshell is examined analytically for large distances andnear the horizon. In the special case, when at largedistances of the hole the attractive Newtongravitational force is compensated by the repulsive Coulombforce, the complete motion is given explicitly in termsof elementary functions.     

Entropy Corrections for a Charged Black Hole of String Theory

We study the entropy of the Gibbons-Maeda-Garfinkle-Horowitz-Strominger (GMGHS) charged black hole, originated from the effective action thatemerges in the low-energy of string theory, beyond semiclassical approximations. Applying the properties of exact differentials for three variables to the first law thermodynamics we derive the quantum correctionsto the entropy of the black hole. The leading (logarithmic) and non leading corrections to the area law are obtained.     

Entropy of N-Dimensional Spherically Symmetric Charged Black Hole

By using the method of quantum statistics, we derive directly the partition functions of bosonic andfermionic fields in the N-dimensional spherically symmetric charged black hole space-time. The statistical entropy ofblack hole is obtained by an improved brick-wall method. When we choose proper parameters in our results, we canobtain that the entropy of black hole is proportional to the area of horizon. In our result, there do not exist neglectedterm and divergent logarithmic term given in the original brick-wall method. We avoid the difficulty in solving the waveequation of scalar and Dirac fields. We offer a simple and direct way of studying entropy of the higher-dimensional black hole.     

Quantum Thermal Effect of Nonstatic Charged Black Hole

The difficulty of calculating energy-momentumtensors is avoided by finding directly the solution ofKlein–Gordon and Dirac equations near the horizon.Both the location of the event horizon and the Hawking radiation temperature of a nonstatic chargedblack hole are shown. The results indicate that theHawking radiation temperature can be regarded as acompensating effect under the timescaletransformation.     

The Entropy Inside a Charged Black Hole Under Hawking Radiation

Christodoulou and Rovelli have revealed that black holes have big interiors that grow asymptotically linearly with advanced time. Even if the Hawking radiation is taken into account, such interiors remain large. Based on these findings, we investigate the relation between the entropy contained in the maximum interior volume of a charged black hole and the Bekenstein-Hawking entropy using an improved method. We find that, in the early stages of the radiation, the variation of the entropy is proportional to the variation of the Bekenstein-Hawking entropy. As the radiation progresses, the magnitude of the ratio will be gradually decreasing     

The Fermion Tunneling from a Slowly Varying Charged Black Hole

According to the Dirac equation and the Rarita-Schwinger equation, the Hamilton-Jacobi equation in curved space-time for the spin 1/2 and 3/2 fermions have been derived. Therefore, we find the Hamilton-Jacobi equation is a fundamental equation in the semiclassical theory. By utilizing this Hamilton-Jacobi equation, we investigate the quantum tunneling radiation from slowly varying Reissner-Nordström (R-N) black hole. The results show that the Hawking temperature do not only related to the properties of slowly varying R-N black hole, but also depended on the time. Meanwhile, it finds that the Hamilton-Jacobi equation can help people more easily and effectively calculated thermodynamic properties black hole.

     

Charged Fermions Tunneling from a Rotating Charged Black Hole in 5-Dimensional Gauged Supergravity

Recent research shows that Hawking radiation from black hole horizon can be treated as a quantum tunneling process, and fermions tunneling method can successfully recover Hawking temperature. In this tunneling framework, choosing a set of appropriate matrices γ^μ is an important technique for fermions tunneling method. In this paper, motivated by Kerner and Man＇s fermions tunneling method of 4 dimension black holes, we further improve the analysis to investigate Hawking tunneling radiation from a rotating charged black hole in 5-dimensional gauged supergravity by constructing a set of appropriate matrices γ^μ for general covariant Dirac equation. Finally, the expected Hawking temperature of the black hole is correctly recovered, which takes the same form as that obtained by other methods. This method is universal, and can also be directly extend to the other different-type 5-dimensional charged black holes.     

Charged Fermions Tunneling from a Rotating Charged Black Hole in 5-Dimensional Gauged Supergravity

Recent research shows that Hawking radiation from black hole horizoncan be treated as a quantum tunneling process, and fermions tunneling method can successfully recover Hawking temperature. In this tunneling framework, choosing a set of appropriate matrices γ^μ is an important technique for fermions tunneling method. In this paper, motivated by Kerner and Man's fermions tunneling method of 4 dimension black holes, we further improve the analysis to investigate Hawking tunneling radiation from a rotating charged black hole in 5-dimensional gauged supergravity byconstructing a set of appropriate matrices γ^μ for general covariant Dirac equation. Finally, the expected Hawking temperature of the black hole is correctly recovered, which takes the same form as that obtained by other methods. This method is universal, and can also be directly extend to the other different-type 5-dimensional charged black holes.     

Accretion onto the Magnetically Charged Regular Black Hole

We investigate the accretion process for static spherically symmetric geometry, i.e., magnetically charged regular black hole with isotropic fluid. We obtain generalized expressions for the velocity(u(r)), speed of sound(c_s~2),energy density(ρ(r)) and accretion rate(M) at the critical point near the regular black hole during the accretion process. We also plot these physical parameters against fixed values of charge, mass and different values of equation of state parameter to study the process of accretion. We find that radial velocity and energy density of the fluid remain positive and negative as well as rate of change of mass is increased and decreased for dust, stiff,quintessence fluid and phantom-like fluid, respectively.     

Non-Singular Charged Black Hole Solution for Non-Linear Source

A non-singular exact black hole solution inGeneral Relativity is presented. The source is anon-linear electrodynamic field, which reduces to theMaxwell theory for weak field. The solution corresponds to a charged black hole with |q| 2s_cm 0.6 m, having metric, curvatureinvariants, and electric field boundedeverywhere.     

Massive Charged Quasinormal Modes of a Reissner-Nordström Black Hole

Using the WKB method and HYBRD program, we evaluate the low-lying massive charged scalar and Dirac field quasinormal modes (QNMs) of a Reissner-Nordström black hole. We discuss the real and imaginary parts of QNMs vary with the charge of black hole, the masses and charges of scalar and Dirac fields.     

Hawking Radiation of Charged Particles in Reissner-NordstrSm Black Hole

We extend the method that Banerjee and Majhi have used to discuss Hawking radiation. Under the condition that the total energy and electrical charge of spacetime are conserved, we investigate Hawking radiation of the charged black hole by a new Tortoise coordinate transformation. Taking the reaction of the radiation of the particle to the spacetime into consideration, we not only derive the radiation spectrum that satisfies the unitary principle in quantum mechanics but also show that the contribution of ingoing particles is equal to the one of outgoing particles on the similar chemical potential term in radiation spectrum caused by charged particles.