scholarly journals Maximal efficiency of the collisional Penrose process

2016 ◽  
Vol 93 (4) ◽  
Author(s):  
Elly Leiderschneider ◽  
Tsvi Piran
Keyword(s):  
Maximal Efficiency ◽  
Penrose Process

scholarly journals Maximal efficiency of the collisional Penrose process with spinning particles

2018 ◽  
Vol 98 (6) ◽  
Author(s):  
Kei-ichi Maeda ◽  
Kazumasa Okabayashi ◽  
Hirotada Okawa
Keyword(s):  
Spinning Particles ◽  
Maximal Efficiency ◽  
Penrose Process

scholarly journals Maximal efficiency of the collisional Penrose process with a spinning particle. II. Collision with a particle on the innermost stable circular orbit

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Kazumasa Okabayashi ◽  
Kei-ichi Maeda
Keyword(s):  
Circular Orbit ◽  
Elastic Collision ◽  
Maximum Efficiency ◽  
Spinning Particle ◽  
Spinning Particles ◽  
Text Input ◽  
Maximal Efficiency ◽  
Stable Circular Orbit ◽  
Penrose Process ◽  
Innermost Stable Circular Orbit

Abstract We analyze the collisional Penrose process between a particle on the innermost stable circular orbit (ISCO) orbit around an extreme Kerr black hole and a particle impinging from infinity. We consider both cases with non-spinning and spinning particles. We evaluate the maximal efficiency, $\eta_{\text{max}}=(\text{extracted energy})/(\text{input energy})$, for the elastic collision of two massive particles and for the photoemission process, in which the ISCO particle will escape to infinity after a collision with a massless impinging particle. For non-spinning particles, the maximum efficiency is $\eta_{\text{max}} \approx 2.562$ for the elastic collision and $\eta_{\text{max}} \approx 7$ for the photoemission process. For spinning particles we obtain the maximal efficiency $\eta_{\text{max}} \approx 8.442$ for the elastic collision and $\eta_{\text{max}} \approx 12.54$ for the photoemission process.

Relativity Made Relatively Easy Volume 2

2021 ◽  
Author(s):  
Andrew M. Steane
Keyword(s):  
General Relativity ◽  
Classical Field Theory ◽  
Weak Field ◽  
Stellar Structure ◽  
Field Equations ◽  
Graduate Course ◽  
Entry Level ◽  
Introductory Course ◽  
Penrose Process ◽  
Low Amplitude

This is a textbook on general relativity and cosmology for a physics undergraduate or an entry-level graduate course. General relativity is the main subject; cosmology is also discussed in considerable detail (enough for a complete introductory course). Part 1 introduces concepts and deals with weak-field applications such as gravitation around ordinary stars, gravimagnetic effects and low-amplitude gravitational waves. The theory is derived in detail and the physical meaning explained. Sources, energy and detection of gravitational radiation are discussed. Part 2 develops the mathematics of differential geometry, along with physical applications, and discusses the exact treatment of curvature and the field equations. The electromagnetic field and fluid flow are treated, as well as geodesics, redshift, and so on. Part 3 then shows how the field equation is solved in standard cases such as Schwarzschild-Droste, Reissner-Nordstrom, Kerr, and internal stellar structure. Orbits and related phenomena are obtained. Black holes are described in detail, including horizons, wormholes, Penrose process and Hawking radiation. Part 4 covers cosmology, first in terms of metric, then dynamics, structure formation and observational methods. The meaning of cosmic expansion is explained at length. Recombination and last scattering are calculated, and the quantitative analysis of the CMB is sketched. Inflation is introduced briefly but quantitatively. Part 5 is a brief introduction to classical field theory, including spinors and the Dirac equation, proceeding as far as the Einstein-Hilbert action. Throughout the book the emphasis is on making the mathematics as clear as possible, and keeping in touch with physical observations.

scholarly journals Black hole superradiance as a probe of ultra-light new particles

2016 ◽  
Vol 12 (S324) ◽  
pp. 273-278
Author(s):  
Robert Lasenby
Keyword(s):  
Beyond Standard Model ◽  
Black Holes ◽  
Black Hole ◽  
Standard Model ◽  
Gravitational Wave ◽  
Exponential Growth ◽  
Gravitational Radiation ◽  
Bound States ◽  
Penrose Process ◽  
Energy And Momentum

AbstractBosonic fields around a spinning black hole can be amplified via ‘superradiance’, a wave analogue of the Penrose process, which extracts energy and momentum from the black hole. For hypothetical ultra-light bosons, with Compton wavelengths on ≳ km scales, such a process can lead to the exponential growth of gravitationally bound states around astrophysical Kerr black holes. If such particles exist, as predicted in many theories of beyond Standard Model physics, then these bosonic clouds give rise to a number of potentially-observable signals. Among the most promising are monochromatic gravitational radiation signals which could be detected at Advanced LIGO and future gravitational wave observatories.

scholarly journals Magnetized Black Holes: Ionized Keplerian Disks and Acceleration of Ultra-High Energy Particles

Proceedings ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 13 ◽  
Author(s):  
Zdeněk Stuchlík ◽  
Martin Kološ ◽  
Arman Tursunov
Keyword(s):  
Magnetic Field ◽  
Black Holes ◽  
Magnetic Fields ◽  
High Energy ◽  
Weak Magnetic Fields ◽  
Motion Transformation ◽  
Penrose Process ◽  
Field Lines ◽  
High Energy Particles ◽  
Quasiperiodic Oscillations

Properties of charged particle motion in the field of magnetized black holes (BHs) imply four possible regimes of behavior of ionized Keplerian disks: survival in regular epicyclic motion, transformation into chaotic toroidal state, destruction due to fall into the BHs, destruction due to escape along magnetic field lines (escape to infinity for disks orbiting Kerr BHs). The regime of the epicyclic motion influenced by very weak magnetic fields can be related to the observed high-frequency quasiperiodic oscillations. In the case of very strong magnetic fields particles escaping to infinity could form UHECR due to extremely efficient magnetic Penrose process – protons with energy E > 10 21 eV can be accelerated by supermassive black holes with M ∼ 10 10 M ⊙ immersed in magnetic field with B ∼ 10 4 Gs.

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