Studying X-ray spectra from large-scale jets of Fanaroff-Riley type I radio galaxies: application of shear particle acceleration
Shear acceleration is a promising candidate mechanism for particle acceleration in extragalactic relativistic jets. For this study, we explored the application of the shear acceleration model to 17 X-ray-bright jet regions in the large-scale jets of Fanaroff-Riley (FR) type I radio galaxies. We stud...
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| Main Authors: | , , , , , , , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
April 2026
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| In: |
Astronomy and astrophysics
Year: 2026, Volume: 708, Pages: 1-12 |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/202558822 |
| Online Access: | Verlag, kostenfrei, Volltext: https://doi.org/10.1051/0004-6361/202558822 Verlag, kostenfrei, Volltext: https://www.aanda.org/articles/aa/abs/2026/04/aa58822-25/aa58822-25.html 
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| Author Notes: | Jia-Xing Wang, Jia-Chun He, Xiao-Na Sun, Jie-Shuang Wang, Frank M. Rieger, Yun-Feng Liang, Hai-Ming Zhang, and En-Wei Liang |
| Summary: | Shear acceleration is a promising candidate mechanism for particle acceleration in extragalactic relativistic jets. For this study, we explored the application of the shear acceleration model to 17 X-ray-bright jet regions in the large-scale jets of Fanaroff-Riley (FR) type I radio galaxies. We studied the jet properties by fitting the multiwavelength spectral energy distributions (SEDs) in a leptonic framework including synchrotron radiation and inverse-Compton scattering off the cosmic microwave background photons. In order to improve spectral modeling, we analyzed <i>Fermi<i/>-LAT data for four sources and reanalyzed archival data of <i>Chandra<i/> on three X-ray-bright jet regions. We show that synchrotron radiation from a second, shear-accelerated electron population reaching multi-TeV energies satisfactorily models the X-ray SEDs. We explored three different velocity profiles, including linearly decreasing, power-law, and Gaussian profiles and we find that the inferred jet spine velocities are significantly dependent on the choice of velocity profile. The derived magnetic field strengths range from a few to several tens of μG, and the required power in nonthermal particles is well below the Eddington constraint. For M 87, we find that the summed emission from all jet knots is comparable to H.E.S.S. low-state flux, suggesting that the large-scale jet may play a dominant role for the persistent very high energy emission. A comparison with previous results for FR II jets shows that FR I jets tend to have stronger magnetic fields but lower total electron energy. The larger shear viscosity (slower flows and softer shear electron spectral indices) of FR I jets may imply enhanced entrainment and stronger jet-environment interactions compared to FR II jets. Finally, we discuss the potential contribution of FR I jets to ultra-high-energy cosmic rays. |
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| Item Description: | Online veröffentlicht: 24. April 2026 Gesehen am 10.06.2026 |
| Physical Description: | Online Resource |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/202558822 |