3D-MHD simulations of the evolution of magnetic fields in FR II radio sources

TL;DR

This paper uses 3D-MHD simulations to analyze magnetic field evolution in FR II radio sources, revealing how jet dynamics and viewing angles influence magnetic structures and polarization properties.

Contribution

It introduces comprehensive 3D-MHD simulations of bipolar jets with synthetic observations, highlighting the role of backflow and turbulence in magnetic field shaping.

Findings

Synthetic polarization maps match observations.

Magnetic fields are shaped by jet backflow.

Turbulence develops in evolved sources.

Abstract

3D-MHD numerical simulations of bipolar, hypersonic, weakly magnetized jets and synthetic synchrotron observations are presented to study the structure and evolution of magnetic fields in FR II radio sources. The magnetic field setup in the jet is initially random. The power of the jets as well as the observational viewing angle are investigated. We find that synthetic polarization maps agree with observations and show that magnetic fields inside the sources are shaped by the jets' backflow. Polarimetry statistics correlates with time, the viewing angle and the jet-to-ambient density contrast. The magnetic structure inside thin elongated sources is more uniform than for ones with fatter cocoons. Jets increase the magnetic energy in cocoons, in proportion to the jet velocity. Both, filaments in synthetic emission maps and 3D magnetic power spectra suggest that turbulence develops in evolved sources.