Particle collisions near static spherically symmetric black holes

Hackmann, Eva; Nandan, Hemwati; Sheoran, Pankaj

doi:10.1016/j.physletb.2020.135850

Cited by 13 publications

(19 citation statements)

References 19 publications

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“…The difference with respect to the BSW setup is that only one of the colliding particles comes from infinity while the other particle (the target particle) is created (or placed) close to the horizon. The latter feature means that the energy parameter of the particle trajectory of this second particle is small, which can be used to show that even in a non-rotating black hole spacetime, arbitrarily large center of mass energies can be achieved [19]. Following the same idea, a similar result can be derived in the case in which the spin of the particles is also taken into account [20].…”

Section: Introductionmentioning

confidence: 86%

“…Again we assume that the particles are neutral q 1 = q 2 = 0. This scenario was originally suggested for non-rotating black holes in [19].…”

Section: Near-horizon Target Particle With Small Energy and Zero Angu...mentioning

confidence: 92%

“…A second possibility is that the energy of one of the particles is very small but non-vanishing and that its angular momentum is zero, which can be seen by applying a power series expansion for small E 1 or E 2 to (7). For non-rotating black holes, this applies without any constraint on the angular momentum of the particle, as has been pointed out in [19]. For rotating black holes, there exists the possibility of particle trajectories in the ergosphere with vanishing energy parameter, which would lead to a divergence in the last term of (7).…”

Section: Particle Motion In Kerr-newman Black Hole Geometrymentioning

confidence: 99%

“…In [19] the possibility of an arbitrarily large center of mass energy was discussed for the non-rotating and noncharged black hole. From the results for the general Kerr-Newman spacetime, we find the influence of the hoop conjecture for this case by setting a = 0 and τ = 1.…”

Section: The Hoop Conjecture In Schwarzschild Geometrymentioning

confidence: 99%

“…More recently, an alternative mechanism, leading to infinite center of mass energies in collisions non-rotating black hole spacetimes, has been proposed [19]. The difference with respect to the BSW setup is that only one of the colliding particles comes from infinity while the other particle (the target particle) is created (or placed) close to the horizon.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

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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Section: Introductionmentioning

confidence: 86%

“…Again we assume that the particles are neutral q 1 = q 2 = 0. This scenario was originally suggested for non-rotating black holes in [19].…”

Section: Near-horizon Target Particle With Small Energy and Zero Angu...mentioning

confidence: 92%