Related papers: On the Penrose process for rotating black holes
The mass of a black hole is interpreted, in terms of thermodynamic potentials, as being the enthalpy, with the pressure given by the cosmological constant. The volume is then defined as being the Legendre transform of the pressure and the…
We study physical processes around a rotating black hole in pure Gauss-Bonnet (GB) gravity. In pure GB gravity, gravitational potential has slower fall off as compared to the corresponding Einstein potential in the same dimension. It is…
We derive a compact, covariant expression for the relative Lorentz factor of two particles in curved spacetime and apply it to particle decay in Kerr spacetime. This allows us to show that energy conservation in the local center-of-mass…
Recent general relativistic MHD simulations have suggested that relativistic jets from active galactic nuclei (AGNs) have been powered by rotational energy of central black holes. Some mechanisms of extraction of black hole rotational…
A critique of the singularity theorems of Penrose, Hawking, and Geroch is given. It is pointed out that a gravitationally collapsing black hole acts as an ultrahigh energy particle accelerator that can accelerate particles to energies…
We present a novel approach which produces Dark Matter jets along the rotation axis of Kerr black holes utilizing the Penrose process. The properties of these jets are investigated, as well as their potential to create Dark Matter…
We study energy extraction and particle acceleration in the rotating Einstein-Maxwell-Dilaton-Axion (EMDA) black hole, focusing on the impact of dilaton hair $b\le 0$ on near-horizon energetics relative to Kerr. For the Penrose process we…
This paper explores the dynamics of particles in higher dimensions. For this purpose, we discuss some interesting features related to the motion of particles near Myers-Perry black hole with arbitrary extra dimensions as well as single…
In this article, we study the repetitive Penrose process for the Kerr-Taub-NUT black hole (BH). First of all, we briefly review the spacetime of the Kerr-Taub-NUT BH, including horizon and ergosphere structures. The results indicate that…
Let a particle move in the flat space-time under the action of the electric potential. If it decays to two fragments, the energy of debris can be larger than the original energy and, moreover, the efficiency of such a process can be…
According to Penrose effect, particles with negative energy can exist in the ergospheres of rotating black holes. We analyze geodesics for such particles and show that there are no circular and elliptic orbits in the ergosphere of a…
We consider the interaction between a plane wave and a (counter-moving) black hole. We show that energy is transferred from the black hole to the wave, giving rise to a negative absorption cross-section. Moving black holes absorb radiation…
The most general formulation of Penrose's inequality yields a lower bound for ADM mass in terms of the area, charge, and angular momentum of black holes. This inequality is in turn equivalent to an upper and lower bound for the area in…
Properties of particles in Kerr metric are compared with properties of particles in rotating coordinates in Minkowski space-time. It is shown that particles with negative and zero energies existing in the ergosphere of the rotating black…
During the three decades since its theoretical discovery the Blandford-Znajek process of extracting the rotational energy of black holes has become one of the foundation stones in the building of modern relativistic astrophysics. However,…
We rederive the equations of motion for relativistic strings, that is, one-dimensional elastic bodies whose internal energy depends only on their stretching, and use them to study circular string loops rotating in the equatorial plane of…
We define and sketch the generalized ergosphere of the Majumdar-Papapetrou (MP) spacetime. In particular, we demonstrate the existence of closed orbits of negative energy that live outside the event horizon of such a spacetime. Relying on…
In the present paper, we explore various gravitational aspects such as energy extraction (via the Penrose process and Superradiance), particle collisions around a $\mathcal{N}=2$, $U(1)^2$ dyonic rotating black hole (BH) in the gauged…
The classical Penrose inequality, a relation between the ADM mass and the area of any cross section of the black hole event horizon, was introduced as a test of the weak cosmic censorship conjecture: if it fails, the trapped surface is not…
The stationary, spherically symmetric accretion of dark energy onto a Schwarzschild black hole is considered in terms of relativistic hydrodynamics. The approximation of an ideal fluid is used to model the dark energy. General expressions…