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Particle acceleration in shearing flows: the self-generation of turbulent spine-sheath structures in relativistic magnetohydrodynamic jet simulations

X-ray observations of kiloparsec-scale extragalactic jets favour a synchrotron origin. The short cooling times of the emitting electrons require a distributed acceleration of electrons up to sub-PeV energies. In a previous paper, we found that this can be self-consistently explained by a shear accel...

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Bibliographic Details
Main Authors: Wang, Jie-Shuang (Author) , Reville, Brian (Author) , Mizuno, Yosuke (Author) , Rieger, Frank M. (Author) , Aharonian, Felix A (Author)
Format: Article (Journal)
Language:English
Published: February 2023
In: Monthly notices of the Royal Astronomical Society
Year: 2023, Volume: 519, Issue: 2, Pages: 1872-1880
ISSN:1365-2966
DOI:10.1093/mnras/stac3616
Online Access:Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1093/mnras/stac3616
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Author Notes:Jie-Shuang Wang, Brian Reville, Yosuke Mizuno, Frank M. Rieger and Felix A. Aharonian
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Summary:X-ray observations of kiloparsec-scale extragalactic jets favour a synchrotron origin. The short cooling times of the emitting electrons require a distributed acceleration of electrons up to sub-PeV energies. In a previous paper, we found that this can be self-consistently explained by a shear acceleration model, where particles are accelerated to produce power-law spectra, with the spectral index being determined mainly by the velocity profile and turbulence spectrum. In this paper, we perform 3D relativistic magnetohydrodynamic simulations to investigate the formation of a spine-sheath structure and the development of turbulence for a relativistic jet propagating into a static cocoon. We explore different spine velocities and magnetic field profiles, with values being chosen to match typical Fanaroff-Riley type I/II jets. We find that in all cases a sheath is generated on the interface of the spine and the cocoon mainly as a result of the Kelvin-Helmholtz instability. The large-scale velocity profile in the sheath is close to linear. Turbulence develops in both the spine and the sheath, with a turbulent velocity spectrum consistent with Kolmogorov scaling. The implications for shear particle acceleration are explored, with a focus on the particle spectral index.
Item Description:Veröffentlicht: 30. Dezember 2022
Gesehen am 29.03.2023
Physical Description:Online Resource
ISSN:1365-2966
DOI:10.1093/mnras/stac3616

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