Related papers: Energy Extraction and Particle Acceleration in Str…
Recently, a class of exact solutions describing rotating black holes immersed in a uniform magnetic field has been proposed, and various properties of such black holes remain unclear. This paper aims to explore how to extract energy based…
String inspired models can serve as potential candidates to replace GR in the high energy regime where quantum gravity is expected to play a vital role. Such models not only subsume the ultraviolet nature of gravity but also exhibit…
Einstein-Maxwell dilaton-axion (EMDA) gravity provides a simple framework to investigate the signatures of string theory. The axion and the dilaton fields arising in EMDA gravity have important implications in inflationary cosmology and in…
The possibility of mining the rotational energy from black holes has far--reaching implications. Such energy extraction could occur even for isolated black holes, if hypothetical ultralight bosonic particles exist in Nature, leading to a…
The exact analytic solutions of the Maxwell equations in the exterior of a boosted rotating black hole immersed in an external magnetic field are obtained. The effect of boost as well as electromagnetic field on charged particle motion and…
We analyze collisional Penrose process of spinning test particles in an extreme Kerr black hole. We consider that two particles plunge into the black hole from infinity and collide near the black hole. For the collision of two massive…
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.…
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…
The low-energy effective action of String Theory introduces corrections to the dilaton-graviton sector, resulting in deformed black holes beyond general relativity. We analyze extreme mass-ratio inspiral systems (EMRIs), where a…
The hidden conformal symmetry of extreme and non-extreme Einstein-Maxwell-Dilaton-Axion (EMDA) black holes is addressed in this paper. For the non-extreme one, employing the wave equation of massless scalars, the conformal symmetry with…
We investigate the electric Penrose process in Ay\'{o}n-Beato-Garc\'{i}a (ABG) black holes, both in the presence and absence of a cosmological constant, presenting the first such analysis within the context of regular black holes. Our study…
Using the Kerr-Schild formalism to solve the Einstein-Maxwell equations, we study energy transport due to time-dependent electromagnetic perturbations around a Kerr black hole, which may work as a mechanism to illuminate a disk located on…
Extracting the rotational energy from a Kerr black hole (BH) is one of the crucial topics in relativistic astrophysics. Here, we give special attention to the Penrose ballistic process based on the fission of a massive particle $\mu_0$ into…
We study a recursive Penrose process and the energy extraction for the decay of electrically charged particles in a Reissner-Nordstr\"om black hole spacetime with anti-de Sitter (AdS) asymptotics, incorporating the backreaction on the black…
The mass--energy formula of black holes implies that up to 50% of the energy can be extracted from a static black hole. Such a result is reexamined using the recently established analytic formulas for the collapse of a shell and expression…
By performing two-dimensional axisymmetric general relativistic radiation magnetohydrodynamics simulations with spin parameter $a^*$ varying from -0.9 to 0.9, we investigate the dependence on the black hole spin of the energy flow from…
The energy extraction from an electrostatic black hole by the decay or splitting of electrically charged particles is analyzed. We determine the energetic conditions that make the extraction process viable and present a general expression…
A new scenario for extracting energy from a Kerr black hole is proposed. With magnetic field lines connecting plasma particles inside the ergosphere with remote loads, the frame dragging twists the field lines so that energy and angular…
We first study the escape probability of the spinning particle emitted from the Kerr black hole and find that the escape probability increases with the spin of the particle around the extreme Kerr black hole; in contrast, the escape…
Production and acceleration mechanisms of ultra-high-energy cosmic rays (UHECRs) of energy $>10^{20}$eV, clearly beyond the GZK-cutoff limit remain unclear that points to exotic nature of the phenomena. Recent observations of extragalactic…