Ray-Tracing in Relativistic Jet Simulations: A Polarimetric Study of Magnetic Field Morphology and Electron Scaling Relations

TL;DR

This study uses 3D relativistic MHD simulations and polarized radiative transfer to analyze how magnetic field structures in AGN jets influence their polarized synchrotron emission, providing synthetic radio maps for different magnetic morphologies.

Contribution

It introduces a comprehensive simulation framework combining RMHD and polarized radiative transfer to connect magnetic field morphology with observable polarization features in relativistic jets.

Findings

Toroidal magnetic fields cause edge-brightened emission

Poloidal magnetic fields cause spine-brightened emission

Circular polarization varies with magnetic field orientation

Abstract

The jets emanating from the centers of active galactic nuclei (AGN) are among the most energetic objects in the universe. Investigating how the morphology of the jet's synchrotron emission depends on the magnetic nature of the jet's relativistic plasma is fundamental to the comparison between numerical simulations and the observed polarization of relativistic jets. Through the use of 3D relativistic magnetohydrodynamic (RMHD) jet simulations (computed using the PLUTO code) we study how the jet's synchrotron emission depends upon the morphology of the jet's magnetic field structure. Through the application of polarized radiative transfer and ray-tracing (via the RADMC-3D code) we create synthetic radio maps of the jet's total intensity as well as the linearly and circularly polarized intensity for each jet simulation. In particular, we create synthetic ray-traced images of the jet's polarized synchrotron emission when the jet carries a predominantly poloidal, helical, and toroidal magnetic field. We also explore several scaling relations in which the underlying electron power-law distribution is set proportional to: (i) the jet's thermal plasma density, (ii) the jet's internal energy density, and (iii) the jet's magnetic energy density. We find that: (i) the jet emission is edge brightened when the magnetic field is toroidal in nature and spine brightened when the magnetic field is poloidal in nature, (ii) the circularly polarized emission exhibits both negative and positive signs for the toroidal magnetic field morphology at an inclination of 45{\deg} as well as 5{\deg}, and (iii) the relativistic jet's emission is largely independent of different emission scaling relations when the ambient medium is excluded.