Particle acceleration in shearing flows: the case for large-scale jets
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 p...
Saved in:
| Main Authors: | , , , , |
|---|---|
| Format: | Article (Journal) |
| Language: | English |
| Published: |
2021 May 21
|
| In: |
Monthly notices of the Royal Astronomical Society
Year: 2021, Volume: 505, Issue: 1, Pages: 1334-1341 |
| ISSN: | 1365-2966 |
| DOI: | 10.1093/mnras/stab1458 |
| Online Access: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1093/mnras/stab1458 Verlag, lizenzpflichtig, Volltext: https://academic.oup.com/mnras/article/505/1/1334/6279671 
|
| Author Notes: | Jie-Shuang Wang, Brian Reville, Ruo-Yu Liu, Frank M. Rieger and Felix A. Aharonian |
| Summary: | 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. |
|---|---|
| Item Description: | Gesehen am 17.09.2021 |
| Physical Description: | Online Resource |
| ISSN: | 1365-2966 |
| DOI: | 10.1093/mnras/stab1458 |