Influence of Density Distribution on Synchrotron Polarization Dispersion in Magnetized Interstellar Medium

TL;DR

This paper introduces the polarization frequency analysis (PFA) as a new method to study turbulent magnetic fields in the interstellar medium, effectively revealing magnetic turbulence properties while avoiding Faraday depolarization effects.

Contribution

The work develops and applies PFA to synthetic data, demonstrating its ability to determine magnetic turbulence scaling slopes under different density-magnetic field coupling conditions.

Findings

PFA can reveal the scaling slope of turbulent magnetic fields with weak coupling.

PFA reflects the RM scaling slope in strong coupling scenarios.

PFA avoids Faraday depolarization, making it promising for observational data analysis.

Abstract

Faraday rotation measure (RM) synthesis is a well-known approach originated in Burn (1966) and later developed by Brentjens \& de Bruyn (2005) for studying magnetic fields. This work presents a complementary approach--the polarization frequency analysis (PFA)--allowing for the properties of the turbulent magnetic field, which are difficult to include in Burn's original approach. Based on synthetic polarization observation of magnetohydrodynamic turbulence simulation data, we study the influence of the coupling effect between density and magnetic field on synchrotron polarization dispersion. By applying the PFA to different simulated interstellar turbulence environments, we find that the PFA technique can reveal the scaling slope of the turbulent magnetic field in the case of a weak coupling effect and can also reflect the scaling slope of the RM in the case of a strong coupling effect. Since it avoids the influence of Faraday depolarization, the PFA technique is a promising way to uncover turbulence properties using observational data from the Low-Frequency Array for Radio Astronomy and the Square Kilometre Array.