Particle acceleration in shearing flows

• Verfasst von: Wang, Jie-Shuang [VerfasserIn]
• Verfasst von: Reville, Brian [VerfasserIn]
• Verfasst von: Liu, Ruo-Yu [VerfasserIn]
• Verfasst von: Rieger, Frank M. [VerfasserIn]
• Verfasst von: Aharonian, Felix A [VerfasserIn]
• Titel: Particle acceleration in shearing flows
• Titelzusatz: the case for large-scale jets
• Verf.angabe: Jie-Shuang Wang, Brian Reville, Ruo-Yu Liu, Frank M. Rieger and Felix A. Aharonian
• E-Jahr: 2021
• Jahr: 2021 May 21
• Umfang: 8 S.
• Teil: volume:505
• Teil: year:2021
• Teil: number:1
• Teil: month:07
• Teil: pages:1334-1341
• Teil: extent:8
• Fussnoten: Gesehen am 17.09.2021
• Titel Quelle: Enthalten in: Royal Astronomical SocietyMonthly notices of the Royal Astronomical Society
• Ort Quelle: Oxford : Oxford Univ. Press, 1827
• Jahr Quelle: 2021
• Band/Heft Quelle: 505(2021), 1 vom: Juli, Seite 1334-1341
• ISSN Quelle: 1365-2966
• DOI: doi:10.1093/mnras/stab1458
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 177087769X

Abstract

X-ray observations of kiloparsec-scale jets indicate that a synchrotron origin of the sustained non-thermal emission is likely. This requires distributed acceleration of electrons up to near PeV energies along the jet. The underlying acceleration mechanism is still unclear. Shear acceleration is a promising candidate, as velocity-shear stratification is a natural consequence of the collimated flow of a jet. We study the details of shear acceleration by solving the steady-state Fokker-Planck-type equation and provide a simple general solution for trans-relativistic jets for a range of magnetohydrodynamic turbulent power-law spectra. In general, the accelerated particle population is a power-law spectrum with an exponential-like cut-off, where the power-law index is determined by the turbulence spectrum and the balance of escape and acceleration of particles. Adopting a simple linearly decreasing velocity profile in the boundary of large-scale jets, we find that the multiwavelength spectral energy distribution of X-ray jets, such as Centaurus A and 3C 273, can be reproduced with electrons that are accelerated up to ∼PeV. In kpc-scale jets, protons may be accelerated up to ∼EeV, supporting the hypothesis that large-scale jets are strong candidates for ultra-high-energy-cosmic ray sources within the framework of shear acceleration.