GeV-TeV gamma-rays produced by electrons in the kpc scale jet as a result of comptonization of the inner jet emission

Abstract

A few radio galaxies have been discovered to emit GeV-TeV gamma-ray emission in spite of relatively large viewing angles of their jets. We consider a scenario in which such large angle gamma-ray emission is preferentially produced by isotropically distributed relativistic electrons in the kpc scale jet. These electrons comptonize soft, non-thermal radiation from the inner jet which is beamed due to its relativistic motion. In terms of such a model, we interpret recently discovered TeV gamma-ray emission from the kpc scale jets in Cen~A. Interestingly, due to the geometry of the inverse Compton scattering process, intensity of the gamma-ray emission from the counter-jet is predicted to be on a higher level than the emission from the jet. This is true provided that both, a jet and a counter-jet, are twins, i.e. the physical processes in the jet and counter-jet result in the acceleration of particles in a similar way. However, in general, the jet and counter-jet can differ significantly. Therefore, their relative contribution to the gamma-ray emission from the jets in Cen~A can become more complicated. Investigation of the distribution of the TeV gamma-ray emission along jets of nearby radio galaxies with the next generation telescopes should provide constraints on the considered model and the content of the kpc-scale jets.

12 pages, 4 figures, MNRAS accepted

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• Nuclear and electromagnetic cascades induced by ultrahigh-energy cosmic rays in radio galaxies: implications for Centaurus A
• Inverse Compton scattering of starlight in the kiloparsec-scale jet in Centaurus A: The origin of excess TeV $\gamma$-ray emission
• Interpreting correlated observations of cosmic rays and gamma-rays from Centaurus A with a proton blazar inspired model
• Physical Conditions and Particle Acceleration in the Kiloparsec Jet of Centaurus A
• Morphology of TeV gamma-ray emission from the kpc scale jets in radio galaxies
• The High Energy View of FR0 Radio Galaxies