Tracing 3-D Magnetic Field Structure Using Dust Polarization and the Zeeman Effect

TL;DR

This paper develops a method to infer the three-dimensional magnetic field structure in molecular clouds by combining dust polarization and Zeeman effect observations, validated through synthetic simulations.

Contribution

It introduces a novel approach to derive magnetic field inclination and strength using combined dust polarization and Zeeman data, supported by simulation analysis.

Findings

Dust polarization can determine inclination angle in certain cloud conditions.

Magnetic field strength can be estimated by comparing polarization and Zeeman observations.

Polarization angle dispersion relates to the Alfvén Mach Number and magnetic field orientation.

Abstract

The characterization of magnetic fields within molecular clouds is fundamental to understanding star formation processes. Accurately gauging the three-dimensional structure of these fields presents a challenge, as observational techniques such as dust polarization and the Zeeman effect each provide only partial information on the orientation and line-of-sight strength, respectively. By analyzing a suite of AREPO simulations, this paper investigates how observables can relate to underlying physical properties to derive a more comprehensive picture of the magnetic field's inclination angle and strength, specifically in regions where both dust polarization and Zeeman data are available. To demonstrate the method, we produce synthetic observations of the polarization angle dispersion and line-of-sight Alfv\'en Mach Number and explore the behavior of the inclination angle, $\gamma$, and strength of the magnetic field in regions where both Zeeman and dust polarization data are available. We find that dust polarization data can be used to determine the inclination angle if the cloud is known to be trans-Alfv\'enic or sub-Alfv\'enic. The strength of the magnetic field relative to turbulence can be estimated by comparing polarization observations to Zeeman observations. Comparing the dispersion of the polarization angle to the estimated line-of-sight Alfv\'en Mach Number provides clues about the strength of the magnetic field and, consequently, the orientation of the magnetic field.