Related papers: Energy Extraction from a Rotating Black Hole by Ma…
The highest efficiency of converting rest mass into energy by accreting matter into a Kerr black hole is ~ 31% (Thorne 1974). We propose a new process in which periods of accretion from a thin disk, and the associated spin-up of the black…
We study properties of particles with zero or negative energy and a nonzero orbital angular momentum in the ergosphere of a rotating black hole. We show that the sign of the particle energy is uniquely determined by the angular velocity of…
Superradiance is known as a wave amplification process caused by rotating or charged black holes. We argue that the superradiance of stationary black holes in asymptotically AdS spacetimes can be characterized by the ability of energy…
The heat engine of magnetic black holes in Einstein-AdS gravity coupled to rational nonlinear electrodynamics, as the working substance, is studied. The dynamical negative cosmological constant is considered as a thermodynamic pressure. We…
When magnetic field lines thread a rotating black hole's horizon and connect with remote astrophysical loads, the rotational energy of the black hole can be extracted through the Blandford-Znajek mechanism. Due to the rotation of the black…
Recently, references [1,2] found that the repetitive Penrose process cannot extract all the extractable rotational energy of a Kerr black hole, and reference [3] found that the repetitive electric Penrose process cannot extract all the…
Using long-duration general relativistic magnetohydrodynamic simulations of radiatively inefficient accretion discs, the energy, momentum and mass outflow rates from such systems are estimated. Outflows occur via two fairly distinct modes:…
This is the second lecture of `RAGtime' series on electrodynamical effects near black holes. We will summarize the basic equations of relativistic electrodynamics in terms of spin-coefficient (Newman-Penrose) formalism. The aim of the…
In the MHD description of plasma phenomena the concept of magnetic field lines frozen into the plasma turns out to be very useful. We present here a method of introducing Lagrangian coordinates into relativistic MHD equations in general…
Combined influence of rotation of a black hole and ambient magnetic fields creates conditions for powerful astrophysical processes of accretion and outflow of matter which are observed in many systems across the range of masses; from…
We study electromagnetic radiation reaction on a charged particle around a weakly magnetized Kerr black hole. We solve numerically the Teukolsky equation to find energy fluxes in electromagnetic radiation at the horizon and at spatial…
Recently, Ruffini et al. [Phys. Rev. Lett. 134 (2025) 8, 081403] pointed out that the repetitive Penrose process cannot drain the entire extractable energy of a Kerr black hole. In this Letter, we alternatively point out the charge of a…
Energy extraction from compact objects has been a central topic in general relativity since the introduction of the Penrose process. In this work we present a unified analysis of rotational and electromagnetic energy extraction in Kerr,…
Magnetic Penrose process (MPP) could be highly efficient (efficiency can even exceed $100\%$) for extracting the energy from a Kerr black hole, if it is immersed in a mG order magnetic field. Considering the exact solution of the magnetized…
Recently, it has been discovered that the nonlinear self-interaction of matter can induce energy extraction from black holes beyond superradiant instability. This process is closely associated with the occurrence of a dynamical first-order…
Magnetic reconnection is a ubiquitous plasma process that transforms magnetic energy into particle energy during eruptive events throughout the universe. Reconnection not only converts energy during solar flares and geomagnetic substorms…
States of particles with negative energies are considered for the nonrelativistic and relativistic cases. In nonrelativistic case it is shown that the decays close to the attracting center can lead to the situation similar to the Penrose…
When a black hole evaporates, there arises a net energy flow from the black hole into its outside environment due to the Hawking radiation and the energy accretion onto black hole. Exactly speaking, due to the net energy flow, the black…
We calculate the maximal non-equilibrium work that can be extracted from any mass using information about its micro-state. This is done through the use of black hole thermodynamics in the context of the thermodynamics of information. The…
We study the energetics of a black hole-accretion disk system with magnetic connection: a Keplerian disk is connected to a Kerr black hole by a large-scale magnetic field going through the transition region. We assume that the magnetic…