相关论文: Energy extraction from Kerr black holes by rigidly…

We consider gedanken experiments to destroy Kerr black holes by means of absorbing matter with sufficient energy and angular momentum. It is shown that extremal and near-extremal Kerr black holes cannot be destroyed in a process that…

The specific angular momentum of a Kerr black hole must not be larger than its mass. The observational confirmation of this bound which we call a Kerr bound directly suggests the existence of a black hole. In order to investigate…

The Kerr metric is a vacuum solution of the Einstein equations outside of a rotating black hole, but what interior matter is actually rotating and sourcing the Kerr geometry? Here, we describe a rotating exotic matter which can source the…

Penrose process on rotational energy extraction of the black hole in the Kerr-Taub-NUT spacetime is studied. It has been shown that for the radial motion of particles NUT parameter slightly shifts the shape of the effective potential down.…

The energy extraction from a Einstein-Born-Infeld (EBI) black hole is addressed determining the extension of the ergosphere as well as the extractable energy using the irreducible mass concept. These results are compared with the…

We investigate the conformal string $\sigma $-model corresponding to a general five-dimensional non-extremal black hole solution. In the horizon region the theory reduces to an exactly solvable conformal field theory. We determine the…

Numerous variations have been proposed on the original suggestion by Blandford and Znajek that magnetic fields could be used to extract rotational energy from black holes. A new categorization of these variations is proposed so that they…

If a magnetically dominated magnetosphere is to extract a black hole's rotational energy and transmit it to distant regions, then the inner light surface of that magnetosphere must lie within the ergoregion. That inner light surface…

The deflection of light in the gravitational field of a massive body can be analyzed through diverse theoretical approaches. The null geodesic approach is commonly employed to calculate light deflection within strong and weak field limits.…

Charged black holes, both spherically symmetric and rotating, in the low energy limit of string theory (Einstein-Maxwell-dilaton theory) are compared to analogous geometries in pure general relativity. We describe various physical…

The paper has explored analogue of gravitational synchrotron massive particle and Penrose process in MOdified Gravity (MOG) known as Scalar-Tensor-Vector-Gravity (STVG). Investigation of the gravitational field around Kerr-MOG black hole…

Equations of motion of null cosmic strings near black holes, or other massive sources, are solved exactly in the weak field approximation. The stress-energy tensor of a null string in a curved spacetime is introduced and used to show how…

We consider black holes generically sourced by quantum matter described by regular wavefunctions. This allows for integrable effective energy densities and the removal of Cauchy horizons in spherically symmetric configurations. Moreover, we…

The coupling of a Nambu-Goto string to gravity allows for Schwarzschild black holes whose entropy to area relation is $S=(A/4)(1-4\mu)$, where $\mu$ is the string tension. The departure from $A/4$ universality results from a string…

Kerr black holes have their angular momentum, $J$, bounded by their mass, $M$: $Jc\leqslant GM^2$. There are, however, known black hole solutions violating this Kerr bound. We propose a very simple universal bound on the rotation, rather…

We give a general theory of a rotated black string stream into a rotational horizon in dimension D=5. It is a configuration about one smooth intersection between these two objects when the spacetime is axisymmetric and in the limit that the…

The lack of a positive-definite and conserved energy is a serious obstacle in the black hole stability problem. In this work, we will show that there exists a positive-definite and conserved Hamiltonian energy for axially symmetric linear…

High-energy astrophysical sources such as active galactic nuclei, quasars, X-ray binaries, and gamma-ray bursts are powered by mechanisms that convert gravitational or rotational energy into radiation, jets, and relativistic outflows.…

We present a practical method for calculating the gravitational self-force, as well as the electromagnetic and scalar self forces, for a particle in a generic orbit around a Kerr black hole. In particular, we provide the values of all the…

It is shown that when only the condition} $0<\Omega_{\rm F}<\Omega_{\rm H}$ is satisfied, the Kerr black hole frame-drags its surrounding force-free magnetosphere with the field-line-angular-velocity (FLAV) $\Omega_{\rm F}$, where…