Related papers: Energy Extraction and Particle Acceleration in Str…
Following the interesting work of Ba\~nados, Silk, and West [Phys. Rev. Lett. {\bf 103}, 111102 (2009)], it is repeatedly stated in the physics literature that the center-of-mass energy, ${\cal E}_{\text{c.m}}$, of two colliding particles…
We study rotating black holes in general relativity coupled to nonlinear electrodynamics (NED), focusing on an axisymmetric solution with deformation parameter g. On the spherical seed, weak-field lensing via the Gauss-Bonnet method and the…
In the Penrose process and the Blandford-Znajek mechanism, the rotational energy of a black hole (BH) is extracted via particle fission and magnetic tension, respectively. Recently, inspired by a fundamental trait in plasma astrophysics…
We consider collision of two particles in the vicinity of the extremal acceleration horizon (charged or rotating) that includes the Bertotti-Robinson space-time and the geometry of the Kerr throat. It is shown that the energy in the centre…
We address the properties of extremal black holes by considering the Christodoulou-Ruffini/Hawking mass-energy formula. By simple geometrical arguments, we found that the mass/energy formula is satisfied by two meaningful extremal black…
In this paper, we study the Penrose process and the maximum energy extracted from the collision of two particles near the Kerr-Newman black hole with WGC condition. We consider the collision process when two particles collide in the…
String-inspired models are often believed to provide an interesting framework for quantum gravity and force unification with promising prospects to resolve issues like dark matter and dark energy which cannot be satisfactorily incorporated…
The Comisso-Asenjo mechanism is a novel mechanism proposed recently to extract energy from black holes through magnetic reconnection of the surrounding charged plasma, in which the magnetic field plays a crucial role. In this work, we…
Black holes in Lorentz-violating theories have been claimed to violate the second law of thermodynamics by perpetual motion energy extraction. We revisit this question for a Penrose splitting process in a spherically symmetric setting with…
We investigate the thin disk and shadow of Kerr-Sen black hole in Einstein-Maxwell-dilaton-axion gravity. The results reveal that as the dilaton parameter $r_2$ increase, the energy flux, the radiation temperature, the spectra luminosity,…
The process of particle collision in the vicinity of black holes is known to generate unbounded energies in the center-of-mass frame (the Banados-Silk-West (BSW) effect) under specific conditions. We consider this process in the charged…
We investigate the power of a collisional Penrose process with an unbound energy extraction from an extreme Reissner-Nordstr\"{o}m black hole. This process takes infinite time in a time coordinate at a constant radial coordinate outside of…
As one step towards a systematic modeling of the electromagnetic (EM) emission from an inspiralling black hole binary we consider a simple scenario in which the binary moves in a uniform magnetic field anchored to a distant circumbinary…
Two particles can collide in the vicinity of a rotating black hole producing the divergent energy in the centre of mass frame (the BSW effect). However, it was shown recently that an observer at infinity can register quite modest energies E…
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.…
Shortly after the discovery of the Kerr metric in 1963, it was realized that a region existed outside of the black hole's event horizon where no time-like observer could remain stationary. In 1969, Roger Penrose showed that particles within…
It has been thought for decades that rotating black holes (BHs) power the energetic gamma-ray bursts (GRBs) and active galactic nuclei (AGNs), but the mechanism that extracts the BH energy has remained elusive. We here show that the…
We examine numerically the post-merger regime of two Schwarzschild black holes in non head-on collision. Our treatment is made in the realm of non-axisymmetric Robinson-Trautman spacetimes which are appropriate for the description of the…
This paper examines regular black holes, in particular the Bardeen spacetime where singularities are replaced by non-singular cores. It explores the energy extraction through the charged Penrose process and shows that magnetic charge…
We extend our earlier work on the linearised perturbations of static black holes in Einstein-Maxwell-Dilaton (EMD) theories to the case where the black holes are solutions in an enlarged theory including also an axion. We study the…