Characterizing Magnetized Turbulence in M51

TL;DR

This study analyzes high-resolution synchrotron polarization data of M51 to characterize its magnetized turbulence, revealing correlation lengths, anisotropy, and magnetic field strength ratios consistent with turbulence theories.

Contribution

It provides the first detailed angular dispersion analysis of M51's magnetized turbulence, including correlation scales and anisotropy detection, using high-resolution polarization data.

Findings

Turbulent correlation length scale in M51's regions identified.

Anisotropy in turbulence detected across all analyzed regions.

Turbulent to ordered magnetic field strength ratio measured as approximately 1.

Abstract

We use previously published high-resolution synchrotron polarization data to perform an angular dispersion analysis with the aim of charactering magnetized turbulence in M51. We first analyze three distinct regions (the center of the galaxy, and the northwest and southwest spiral arms) and can clearly discern the turbulent correlation length scale from the width of the magnetized turbulent correlation function for two regions and detect the imprint of anisotropy in the turbulence for all three. Furthermore, analyzing the galaxy as a whole allows us to determine a two-dimensional Gaussian model for the magnetized turbulence in M51. We measure the turbulent correlation scales parallel and perpendicular to the local mean magnetic field to be, respectively, delta_{para} = 98 +/- 5 pc and delta_{perp} = 54 +/- 3 pc, while the turbulent to ordered magnetic field strength ratio is found to be Bt/B0 = 1.01 +/- 0.04. These results are consistent with those of Fletcher et al. (2011), who performed a Faraday rotation dispersion analysis of the same data, and our detection of anisotropy is consistent with current magnetized turbulence theories.