Particle acceleration and high-frequency (X-ray and $γ$-ray) emission in the jets of active galactic nuclei

Abstract

It is suggested that the outflowing plasma in the jets of active galactic nuclei (AGNs) is inhomogeneous and consists of separate clouds. These clouds are strongly magnetized and move away from the central engine at relativistic speeds. The clouds interact with an ambient medium which is assumed to be at rest. In the process of this interaction, particles of the ambient medium are accelerated to high energies at the cloud front and flow ahead of the front. It is shown that the radiation of the accelerated particles may be responsible for the X-ray and $γ$-ray emission from AGN jets. TeV $γ$-ray emission is generated in the inner parts of AGN jets where the Lorentz factor of the cloud fronts is $Γ_0\geq 30$, while GeV $γ$-ray emission emanates from the outer parts of AGN jets where $Γ_0$ is $\sim 10$.