Gradient measurement of synchrotron polarization diagnostic: Application to spatially separated emission and Faraday rotation regions

TL;DR

This paper evaluates the effectiveness of synchrotron polarization gradient techniques in mapping magnetic fields in complex interstellar media with spatially separated emission and Faraday rotation regions, demonstrating its robustness across frequencies.

Contribution

It introduces a method to measure projected magnetic fields using polarization gradients in complex media, outperforming traditional vector methods and accounting for Faraday rotation effects.

Findings

Gradient technique successfully traces magnetic fields regardless of frequency.

Faraday rotation density influences measurement accuracy.

Method applicable to complex astrophysical environments.

Abstract

Considering the spatially separated polarization radiation and Faraday rotation regions to simulate complex interstellar media, we study synchrotron polarization gradient techniques' measurement capabilities. We explore how to trace the direction of projected magnetic field of emitting-source region at the multi-frequency bands, using the gradient technique compared with the traditional polarization vector method. Furthermore, we study how Faraday rotation density in the foreground region, i.e., a product of electron number density and parallel component of magnetic fields along the line of sight, affects the measurement of projected magnetic field. Numerical results show that synchrotron polarization gradient technique could successfully trace projected magnetic field within emitting-source region independent of radio frequency. Accordingly, the gradient technique can measure the magnetic field properties for a complex astrophysical environment.