Knot in Cen A: Stochastic Magnetic Field for Diffusive Synchrotron Radiation?

TL;DR

This paper revisits diffusive synchrotron radiation (DSR) from relativistic electrons in small-scale magnetic fields, proposing turbulence as a magnetic field source and analyzing its spectral features to constrain particle acceleration models.

Contribution

It introduces a revised perturbative approach to DSR and links the stochastic magnetic field generated by turbulence to observed multi-band spectra in Cen A.

Findings

Multi-band spectrum of Cen A's knot matches DSR predictions.

Turbulence-generated magnetic fields influence electron radiation.

Results constrain models of particle acceleration.

Abstract

The emission of relativistic electrons moving in the random and small-scale magnetic field is presented by diffusive synchrotron radiation (DSR). In this Letter, we revisit the perturbative treatment of DSR. We propose that random and small-scale magnetic field might be generated by the turbulence. As an example, multi-band radiation of the knot in Cen A comes from the electrons with energy $\gamma_e\sim 10^3-10^4$ in the magnetic field of $10^{-3}G$. The multi-band spectrum of DSR is well determined by the feature of stochastic magnetic field. These results put strong constraint to the models of particle acceleration.