Non-linear collisional Penrose process: How much energy can a black hole release?

Nakao, Ken Ichi; Okawa, Hirotada; Maeda, Kei Ichi

doi:10.1093/ptep/ptx170

Cited by 8 publications

(5 citation statements)

References 30 publications

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“…However because of lack of the back reaction, it may not reveal the proper upper bound on the efficiency of the energy extraction. In the Reissner-Nordström spacetime, we could perform such an analysis for the collision of charged shells [53]. However it would be difficult to analyze the back reaction effect in Kerr black hole background although it is important.…”

Section: Efficiency Of Inverse Compton Scatteringmentioning

confidence: 99%

Maximal efficiency of the collisional Penrose process with spinning particles

2018

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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 particles, if the spins of particles are s1 ≈ 0.01379µM and s2 ≈ −0.2709µM , we obtain the maximal efficiency is about ηmax = (extracted energy)/(input energy) ≈ 15.01, which is more than twice as large as the case of the collision of non-spinning particles (ηmax ≈ 6.32). We also evaluate the collision of a massless particle without spin and a massive particle with spin (Compton scattering), in which we find the maximal efficiency is ηmax ≈ 26.85 when s2 ≈ −0.2709µM , which should be compared with ηmax ≈ 13.93 for the nonspinning case.

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Section: Efficiency Of Inverse Compton Scatteringmentioning

confidence: 99%

Maximal efficiency of the collisional Penrose process with spinning particles

2018

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“…In [2], Bañados-Silk-West (BSW) observed that collisions of particles with specific angular momentum values produce arbitrarily high center of mass energies in extremal Kerr black hole spacetimes. This collisional Penrose process has been studied for different black hole scenarios, such as non-extremal Kerr [3][4][5][6], Kerr-(anti)de Sitter [7,8], Reissner-Nordström [9,10], and Kerr-Newman [11][12][13] geometries, reproducing the original BSW result. Also, taking into account the spin or the charge of the particles, one still obtains an arbitrarily high center of mass energy for collisions near to the horizon of rotating black holes [14][15][16][17].…”

Section: Introductionmentioning

confidence: 87%

“…Evaluating the squared center of mass energy (5) at the hoop radius (10) we find up to second order in m…”

Section: A Non-extremal Casementioning

confidence: 98%

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Exploring black holes as particle accelerators: hoop-radius, target particles and escaping conditions

Liberati,

Pfeifer,

Relancio

2021

Preprint

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The possibility that rotating black holes could be natural particle accelerators has been subject of intense debate. While it appears that for extremal Kerr black holes arbitrarily high center of mass energies could be achieved, several works pointed out that both theoretical as well as astrophysical arguments would severely dampen the attainable energies. In this work we study particle collisions near Kerr-Newman black holes, by reviewing and extending previously proposed scenarios. Most importantly, we implement the hoop conjecture for all cases and we discuss the astrophysical relevance of these collisional Penrose processes. The outcome of this investigation is that scenarios involving near-horizon target particles are in principle able to attain, sub-Planckian, but still ultra high, center of mass energies of the order of 10 21 − 10 23 eV. Thus, these target particle collisional Penrose processes could contribute to the observed spectrum of ultra high-energy cosmic rays, even if the hoop conjecture is taken into account, and as such deserve further scrutiny in realistic settings.

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“…In [2], Bañados-Silk-West (BSW) observed that collisions of particles with specific angular momentum values produce arbitrarily high center of mass energies in extremal Kerr black hole spacetimes. This collisional Penrose process has been studied for different black hole scenarios, such as non-extremal Kerr [3][4][5][6], Kerr-(anti)de Sitter [7,8], Reissner-Nordström [9,10], and Kerr [11][12][13] geometries, reproducing the original BSW result. Also, taking into account the spin or the charge of the particles, one still obtains an arbitrarily high center of mass energy for collisions near to the horizon of rotating black holes [14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Exploring black holes as particle accelerators: hoop-radius, target particles and escaping conditions

Liberati

Pfeifer

Relancio

2022

J. Cosmol. Astropart. Phys.

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The possibility that rotating black holes could be natural particle accelerators has been subject of intense debate. While it appears that for extremal Kerr black holes arbitrarily high center of mass energies could be achieved, several works pointed out that both theoretical as well as astrophysical arguments would severely dampen the attainable energies. In this work we study particle collisions near Kerr black holes, by reviewing and extending the so far proposed scenarios. Most noticeably, we shall focus on the recently advanced target particle scenarios which were claimed to reach arbitrarily high energies even for Schwarzschild black holes. By implementing the hoop conjecture we show that these scenarios involving near-horizon target particles are in principle able to attain, sub-Planckian, but still ultra-high center of mass energies of the order of 1023–1025 eV even for non-extremal Kerr black holes. Furthermore, analysing the properties of particles produced in such collisions, we find that photons can escape to infinity. However, their energy is only of the order of the energy of the colliding particles and hence relatively low, which is the same conclusion previously reached in the literature about the original Bañados-Silk-West process. This finding points towards a general limitation of collisional Penrose processes, at least for what concerns their primary products.

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Non-linear collisional Penrose process: How much energy can a black hole release?

Cited by 8 publications

References 30 publications

Maximal efficiency of the collisional Penrose process with spinning particles

Maximal efficiency of the collisional Penrose process with spinning particles

Exploring black holes as particle accelerators: hoop-radius, target particles and escaping conditions

Exploring black holes as particle accelerators: hoop-radius, target particles and escaping conditions

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