Scalings of the synchrotron cut-off and turbulent correlation of active galactic nucleus jets

TL;DR

This paper introduces a new analytic model for the synchrotron cut-off frequency in AGN jets, accounting for filamentary turbulence, and constrains filament properties using observational data, revealing many small-scale filaments in certain jets.

Contribution

It presents a novel scaling law for synchrotron cut-off frequency in nonuniform AGN jets and links filament correlation length to observational data, introducing the concept of plasma quantization.

Findings

Derived an upper limit for the synchrotron cut-off frequency independent of magnetic field parameters.

Constrained filament correlation length using observational data from 18 extragalactic sources.

Indicated that BL Lac jets contain numerous small-scale filaments.

Abstract

We propose a new analytic scaling of the cut-off frequency of synchrotron radiation from active galactic nucleus (AGN) jets that are nonuniformly filled with many filaments. The theoretical upper limit is provided independent of magnetic intensity, spectral index, coherence and correlation length of filamentary turbulence, etc., such that \nu_c\simeq 6\times 10^{20}\delta[(r-1)/r]^{4/3}(b/10^{-4}) Hz, where \delta, 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.