Mathematische Miszellen. III

Ostrowski, Alexander

doi:10.1007/978-3-0348-9345-9_11

Cited by 38 publications

(68 citation statements)

References 2 publications

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“…These and related results led to the suggestion that (ultra)relativistic shearing flows might be potential sources of UHE cosmic-ray protons (Ostrowski 1998(Ostrowski , 2000Rieger & Duffy 2004). …”

Section: Conceptual Approaches and Applicationsmentioning

confidence: 89%

Particle Acceleration in Mildly Relativistic Shearing Flows: The Interplay of Systematic and Stochastic Effects, and the Origin of the Extended High-energy Emission in AGN Jets

Liu

Rieger

Aharonian

2017

ApJ

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The origin of the extended X-ray emission in the large-scale jets of active galactic nuclei (AGNs) poses challenges to conventional models of acceleration and emission. Although the electron synchrotron radiation is considered the most feasible radiation mechanism, the formation of the continuous large-scale X-ray structure remains an open issue. As astrophysical jets are expected to exhibit some turbulence and shearing motion, we here investigate the potential of shearing flows to facilitate an extended acceleration of particles and evaluate its impact on the resultant particle distribution. Our treatment incorporates systematic shear and stochastic second-order Fermi effects. We show that for typical parameters applicable to large-scale AGN jets, stochastic second-order Fermi acceleration, which always accompanies shear particle acceleration, can play an important role in facilitating the whole process of particle energization. We study the time-dependent evolution of the resultant particle distribution in the presence of second-order Fermi acceleration, shear acceleration, and synchrotron losses using a simple Fokker-Planck approach and provide illustrations for the possible emergence of a complex (multicomponent) particle energy distribution with different spectral branches. We present examples for typical parameters applicable to large-scale AGN jets, indicating the relevance of the underlying processes for understanding the extended X-ray emission and the origin of ultrahigh-energy cosmic rays.

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Section: Conceptual Approaches and Applicationsmentioning

confidence: 89%

Particle Acceleration in Mildly Relativistic Shearing Flows: The Interplay of Systematic and Stochastic Effects, and the Origin of the Extended High-energy Emission in AGN Jets

Liu

Rieger

Aharonian

2017

ApJ

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“…Rachen & Biermann 1993, Ostrowski 1998. A characteristic feature of the boundary acceleration process in a simple considered model is formation of very flat spectrum of escaping particles.…”

Section: Discussionmentioning

confidence: 99%

“…The problem was extensively discussed in early eighties by Berezhko with collaborators (see the review by Berezhko 1990) and in the diffusive limit by Earl et al (1988) and Jokipii et al (1989). The case of a relativistic jet velocity was considered by Ostrowski (1990Ostrowski ( , 1998Ostrowski ( , 2000. The simulations (Ostrowski 1990, cf.…”

Section: Particle Acceleration At the Jet Boundarymentioning

confidence: 99%

Pressure imbalance of FRII radio source lobes: A role of energetic proton population

Ostrowski¹,

Sikora

2001

AIP Conference Proceedings

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Abstract.Recently Hardcastle & Worrall (2000) analyzed 63 FRII radio galaxies imbedded in the X-ray radiating gas in galaxy clusters and concluded, that pressures inside its lobes seem to be a factor of a few lower than in the surrounding gas. One of explanations of the existing 'blown up' radio lobes is the existence of invisible internal pressure component due to energetic cosmic ray nuclei (protons). Here we discuss a possible mechanism providing these particles in the acceleration processes acting at side boundaries of relativistic jets. The process can accelerate particles to ultra high energies with possibly a very hard spectrum. Its action provides also an additional viscous jet breaking mechanism. The work is still in progress.

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“…The border between these two parts of the jet has been proposed to provide good conditions for the acceleration of particles. In fact, the acceleration of particles at the boundary between relativistic jet and its cocoon was discussed [20,21,22,23]. Nuclei accelerated in such mechanism should spend significant time within the cocoon of the jet in which their distribution is close to isotropic.…”

Section: Nuclei In the Jetmentioning

confidence: 99%

“…Assuming α o ∼ 10, this maximum Lorentz factor is γ max He ≈ 1.5 × 10 9 M 9 B 2 for β = 1 and γ max He ≈ 1.5 × 10 9 M 9 B 2 /r for β = 2. The mechanism of particle acceleration at the jet boundary described above is expected to produce relativistic particles with a flat power law spectrum [20,21,22,23].…”

Section: Pos(icrc2017)1069mentioning

confidence: 99%

TeV-PeV neutrinos from accretion disks around super-massive black holes in active galaxies

Bednarek¹

2017

Proceedings of 35th International Cosmic Ray Conference — PoS(ICRC2017)

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We propose that TeV-PeV neutrinos, recently detected by the IceCube, can be produced by neutrons interacting with the matter of the accretion disks around black holes in active galaxies. Neutrons are extracted from nuclei which are disintegrated in jets of active galaxies. The neutrino spectra, expected from the whole population of the active galaxies, are confronted with the observations. We propose that neutrinos produced in such scenario can explain the extra-galactic neutrino background recently measured by the IceCube neutrino detector, provided that 5% fraction of galaxies is AGN and a few percent of neutrons reach the accretion disk.

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Mathematische Miszellen. III

Cited by 38 publications

References 2 publications

Particle Acceleration in Mildly Relativistic Shearing Flows: The Interplay of Systematic and Stochastic Effects, and the Origin of the Extended High-energy Emission in AGN Jets

Particle Acceleration in Mildly Relativistic Shearing Flows: The Interplay of Systematic and Stochastic Effects, and the Origin of the Extended High-energy Emission in AGN Jets

Pressure imbalance of FRII radio source lobes: A role of energetic proton population

TeV-PeV neutrinos from accretion disks around super-massive black holes in active galaxies

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