Statistical tracing of magnetic fields: comparing and improving the techniques

TL;DR

This paper reviews and compares three statistical methods for analyzing magnetic fields in the interstellar medium using radio data, proposing improvements to enhance their accuracy, speed, and applicability.

Contribution

It introduces enhancements to the CFA and PCAA techniques and highlights the advantages and complementary nature of the Velocity Gradient Technique (VGT).

Findings

Faster calculation method for non-periodic correlation functions in CFA.

Proposed improvements to PCAA for better accuracy.

VGT shows advantages in magnetic field tracing and complements other methods.

Abstract

Magnetohydrodynamic(MHD) turbulence displays velocity anisotropies which reflect the direction of the magnetic field. This anisotropy has led to the development of a number of statistical techniques for studying magnetic fields in the interstellar medium. In this paper, we review and compare three techniques that use radio position-position-velocity data for determining magnetic field strength and morphology : the correlation function anisotropy (CFA), Principal Component Analysis of Anisotropies (PCAA), and the more recent Velocity Gradient Technique (VGT). We compare these three techniques and suggest improvements to the CFA and PCAA techniques to increase their accuracy and versatility. In particular, we suggest and successfully implement a much faster way of calculating non-periodic correlation functions for the CFA. We discuss possible improvements to the current implementation of the PCAA. We show the advantages of the VGT in terms of magnetic field tracing and stress the complementary nature with the other two techniques.