Radiation spectrum of rotating G(o)del black hole and correction entropy

We study the Hawking radiation of the scalar field in the rotating Godel black hole in minimal five-dimensional supergravity. We not only derive radiation spectra that satisfy the unitary principle but also obtain the correction term of Bekenstein-Hawking entropy. The conclusion will help us learn more about the rotating Godel black hole in minimal five-dimensional supergravity. This provides a greater understanding of the thermal radiation of black holes.     

Gyroscope precession frequency analysis of a five-dimensional charged rotating Kaluza-Klein black hole

We study the spin precession frequency of a test gyroscope attached to a stationary observer in the five-dimensional rotating Kaluza-Klein black hole(RKKBH). We derive the conditions under which the test gyroscope moves along a timelike trajectory in this geometry, and the regions where the spin precession frequency diverges. The magnitude of the gyroscope precession frequency around the KK black hole diverges at two spatial locations outside the event horizon. However, in the static case, the behavior of the Lense-Thirring frequency of a gyroscope around the KK black hole is similar to the ordinary Schwarzschild black hole. Since a rotating Kaluza-Klein black hole is a generalization of the Kerr-Newman black hole, we present two mass-independent schemes to distinguish these two spacetimes.     

Black holes in brane worlds

A Kerr metric describing a rotating black hole is obtained on the three brane in a five-dimensional Randall-Sundrum brane world by considering a rotating five-dimensional black string in the bulk. We examine the causal structure of this space-time through the geodesic equations.     

Binary black hole in a double magnetic monopole field

Ambient magnetic fields are thought to play a critical role in black hole jet formation. Furthermore, dual electromagnetic signals could be produced during the inspiral and merger of binary black hole systems. In this paper, we derive the exact solution for the electromagnetic field occurring when a static, axisymmetric binary black hole system is placed in the field of two magnetic or electric monopoles. As a by-product of this derivation, we also find the exact solution of the binary black hole configuration in a magnetic or electric dipole field. The presence of conical singularities in the static black hole binaries represent the gravitational attraction between the black holes that also drag the external two monopole field. We show that these off-balance configurations generate no energy outflows.     

Hawking radiation of five-dimensional rotating black hole

Applying the Damour–Ruffini method, we have considered the Hawking radiation of the five-dimensional rotating black hole. When taking the energy conservation and angular momentum conservation into consideration and considering the reaction of the radiation of the particle to spacetime, we see that the exact radiation spectrum is not purely thermal and the angular momentum of the black hole is quantized.     

Radiation from relativistic particles in nongeodesic motion in a strong gravitational field

The scalar and electromagnetic radiation emitted by relativistic particles moving along the stable nongeodesic trajectories in the Kerr gravitational field are described. Two particular models of the nongeodesic motion are developed involving a slightly charged rotating black hole and a rotating black hole immersed in an external magnetic field.     

Point charge in the vicinty of a Kerr black hole

We derive the expression for the electromagnetic field of a point charge at rest on the symmetry axis near a rotating Kerr black hole. This is a generalization of the previously obtained solution for the field of a point charge near a nonrotating Schwarzschild black hole. Unlike the Schwarzschild case the charge is found to give rise to magnetic fields as seen by a stationary or locally nonrotating observer.     

Particle acceleration in Horava–Lifshitz black holes

In this paper we calculate the center-of-mass energy of two colliding test particles near the rotating and non-rotating Horava–Lifshitz black hole. For the case of a slowly rotating KS solution of Horava–Lifshitz black hole we compare our results with the case of Kerr black holes. We confirm the limited value of the center-of-mass energy for static black holes and unlimited value of the center-of-mass energy for rotating black holes. Numerically, we discuss temperature dependence of the center-of-mass energy on the black hole horizon. We obtain the critical angular momentum of particles. In this limit the center-of-mass energy of two colliding particles in the neighborhood of the rotating Horava–Lifshitz black hole could be arbitrarily high. We found appropriate conditions where the critical angular momentum could have an orbit outside the horizon. Finally, we obtain the center-of-mass energy corresponding to this circle orbit.     

Magnetically charged regular black hole in a model of nonlinear electrodynamics

We obtain a magnetically charged regular black hole in general relativity. The source to the Einstein field equations is nonlinear electrodynamic field in a physically reasonable model of nonlinear electrodynamics (NED). “Physically” here means the NED model is constructed on the basis of three conditions: the Maxwell asymptotic in the weak electromagnetic field limit; the presence of vacuum birefringence phenomenon; and satisfying the weak energy condition (WEC). In addition, we analyze the thermodynamic properties of the regular black hole in two ways. According to the usual black hole thermodynamics, we calculate the heat capacity at constant charge, from which we know the smaller black hole is more stable. We also employ the horizon thermodynamics to discuss the thermodynamic quantities, especially the heat capacity at constant pressure.     

Canonical Entropy and Phase Transition of Rotating Black Hole

Recently, the Hawking radiation of a black hole has been studied using the tunnel effect method. The radiation spectrum of a black hole is derived. By discussing the correction to spectrum of the rotating black hole, we obtain the canonical entropy. The derived canonical entropy is equal to the sum of Bekenstein-Havcking entropy and correction term. The correction term near the critical point is different from the one near others. This difference plays an important role in studying the phase transition of the black hole. The black hole thermal capacity diverges at the critical point. However, the canonical entropy is not a complex number at this point. Thus we think that the phase transition created by this critical point is the second order phase transition. The discussed black hole is a five-dimensional Kerr-AdS black hole. We provide a basis for discussing thermodynamic properties of a higher-dimensional rotating black hole.     

Stationary electromagnetic fields around black holes. II. General solutions and the fields of some special sources near a Kerr black hole

The electromagnetic field of a general stationary source, occurring in the vicinity of a rotating (Kerr) black hole, is obtained by solving the Maxwell and Teukolsky equations. The field is expressed both outside and inside the radius at which the source is located. As examples the fields of point charges, charged rings, current loops, and magnetic dipoles not necessarily located in axisymmetric positions are calculated. The electromagnetic field occurring when a Kerr black hole is placed in an originally uniform magnetic field is derived without assuming the alignment of the direction of the magnetic field and the axis of symmetry of the black hole.We have recently learned that A. King from the University of Hamburg has independently found the vacuum solutions given in Section 2 of the present paper. His work will be published inMathematics Proceedings of the Cambridge Philosophical Society. In another paper (to be published inLettere al Nuovo Cimento) he gives the fields of a stationary point charge and a stationary magnetic monopole.     

Hawking radiation from a five-dimensional Lovelock black hole

We investigate Hawking radiation from a five-dimensional Lovelock black hole using the Hamilton–Jacobi method. The behavior of the rate of radiation is plotted for various values of the ultraviolet correction parameter and the cosmological constant. The results show that, owing to the ultraviolet correction and the presence of dark energy represented by the cosmological constant, the black hole radiates at a slower rate in comparison to the case without ultraviolet correction or cosmological constant. Moreover, the presence of the cosmological constant makes the effect of the ultraviolet correction on the black hole radiation negligible.     

Letter: The Radial Infall of a Highly Relativistic Point Particle into a Kerr Black Hole Along the Symmetry Axis

In this Letter we consider the radial infall along the symmetry axis of an ultra-relativistic point particle into a rotating Kerr black hole. We use the Sasaki-Nakamura formalism to compute the waveform, energy spectra and total energy radiated during this process. We discuss possible connections between these results and the black hole-black hole collision at the speed of light process.     

Motion of charged particles in a spacetime of a five dimensional rotating black hole in a magnetic field

We study the effect of an external magnetic field on the stability of circular motion around a five dimensional Myers–Perry metric. Using the Hamilton–Jacobi formalism we derive the effective potential for the radial motion of charged particles around a five dimensional rotating black hole in a uniform magnetic field. We show that there are stable circular orbits around a five dimensional rotating black hole immersed in a uniform magnetic field.     

General nonextremal rotating charged Gödel black holes in minimal five-dimensional gauged supergravity

I present the general exact solutions for nonextremal rotating charged black holes in the G?del universe of five-dimensional minimal supergravity theory. They are uniquely characterized by four nontrivial parameters: namely, the mass m, the charge q, the Kerr equal rotation parameter a, and the G?del parameter j. I calculate the conserved energy, angular momenta, and charge for the solutions and show that they completely satisfy the first law of black hole thermodynamics. I also study the symmetry and separability of the Hamilton-Jacobi and the massive Klein-Gordon equations in these Einstein-Maxwell-Chern-Simons-G?del black hole backgrounds.     

Charged Rotating Black Hole from Five Dimensional Point of View

It is shown that the usual characteristics of a black hole and of the physical fields produced by it obtain a unified geometrical meaning in the five-dimensional framework. Especially, it is demonstrated that a solution for a rotating black hole with electric and scalar charges can be generated by a boost transformation of the fifth coordinate from the Kerr solution.     

Effect of nonlinear electrodynamics on shadows of slowly rotating black holes

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.     

The universe as a five-dimensional black hole

We show the geometrical equivalence of two five-dimensional metrics, one describing a cosmology which smoothly embeds the standard Friedmann-Robertson-Walker-Lemaître models, and another describing an object which topologically is a black hole. The solutions can be interpreted using either membrane or induced-matter theory. We outline the main physics, wherein the horizon of the black hole is connected to a big bounce in the cosmology, which may in turn be connected to a phase change in the vacuum.