Spectral properties of magnetohydrodnamic turbulence revealed by polarization synchrotron emission with Faraday rotation

TL;DR

This paper demonstrates a method to recover the spectral properties of MHD turbulence from synchrotron polarization data, accounting for Faraday rotation effects, and validates it with synthetic observations and theoretical predictions.

Contribution

The study introduces a technique to extract turbulence spectra from synchrotron polarization, extending previous models to more complex observational scenarios including separated and compounded regions.

Findings

Power spectra reflect perpendicular magnetic field fluctuations at short wavelengths.

Long wavelengths reveal Faraday rotation density fluctuations.

Method successfully recovers turbulence statistics from simulated telescope data.

Abstract

We investigate how to recover the spectral properties of underlying magnetohydrodynamic (MHD) turbulence using fluctuation statistics of synchrotron polarization radiation, based on the synthetic observations. Taking spatially coincident, separated, and compounded synchrotron emission and Faraday rotation regions into account, we extract the power spectrum of synchrotron polarization intensities integrated along the line of sight. Our results demonstrate that in the short wavelength range, the power spectra reflect fluctuation statistics of the perpendicular component of turbulent magnetic fields, and the spectra at long wavelengths reveal the fluctuation of the Faraday rotation density, which is a product of the parallel component of magnetic field and thermal electron density. We find that our numerical results (in the case of spatially coincident regions) are in agreement with the analytical prediction in Lazarian \& Pogosyan (2016), and this theoretical prediction is applicable to more complicated settings, i.e., the spatially separated and compounded regions. We simulate telescopic observations that incorporate the effects of telescope angular resolution and noise, and find that statistics of underlying MHD turbulence can be recovered successfully. We expect that the technique can be applied to a variety of astrophysical environments, with existing synchrotron data cubes and a large number of forthcoming data sets from such as the LOw-Frequency Array for Radio astronomy (LOFAR), the Square Kilometer Array (SKA) and the Five-hundred-meter Aperture Spherical radio Telescope (FAST).