2010MNRAS.409.1120H

We propose a new analytic scaling of the cut-off frequency of synchrotron radiation from active galactic nucleus (AGN) jets that are non-uniformly filled with many filaments. The theoretical upper limit is provided independent of magnetic intensity, spectral index, coherence, correlation length of filamentary turbulence, etc., such that ν_c≃ 6 {x} 10²⁰δ[(r- 1)/r]^4/3 (b/10^–4) Hz, where δ, r and b are the Doppler beaming factor, shock-compression ratio and energy-density ratio of the perturbed/local mean magnetic field of the filaments, respectively. Combining our results with observational data for 18 extragalactic sources, a constraint on the filament correlation length is found, in order to give the number scaling of filaments. The results suggest that, in particular, the jets of compact BL Lacs possess a large number of filaments with transverse size scale smaller than the emission-region size. The novel concept of the quantization of flowing plasma is suggested.