Particle acceleration and magnetic field amplification in the jets of 4C74.26

TL;DR

This paper models the emission from the jet hotspot of quasar 4C74.26, revealing magnetic field decay and limited particle energies, highlighting the role of turbulence and diffusion in particle acceleration.

Contribution

It provides a detailed analysis of magnetic field decay and particle acceleration limits in quasar jets, emphasizing the impact of turbulence on these processes.

Findings

Electrons reach only 0.3 TeV energy.

Magnetic fields decay rapidly behind the shock.

Protons are limited to about 100 TeV energy.

Abstract

We model the multi-wavelength emission in the southern hotspot of the radio quasar 4C74.26. The synchrotron radio emission is resolved near the shock with the MERLIN radio-interferometer, and the rapid decay of this emission behind the shock is interpreted as the decay of the amplified downstream magnetic field as expected for small scale turbulence. Electrons are accelerated to only 0.3 TeV, consistent with a diffusion coefficient many orders of magnitude greater than in the Bohm regime. If the same diffusion coefficient applies to the protons, their maximum energy is only ~100 TeV.