Studying the properties of compressible MHD turbulence by synchrotron fluctuation statistics

Abstract

We study the observable properties of compressible MHD turbulence covering different turbulence regimes, based on synthetic synchrotron observations arising from 3D MHD numerical simulations. Using the synchrotron emissivity and intensity, we first explore how the cosmic ray spectral indices affect the measurements of turbulence properties by employing normalized correlation functions. We then study how the anisotropy of synchrotron total and polarization intensities arising from three fundamental MHD modes vary with the viewing angle, i.e., the angle between the mean magnetic field and the line of sight. We employ the ratio of quadrupole moment to the monopole one (QM) for this purpose. Our numerical results demonstrate that: (1) the two-point correlation function of synchrotron statistics for the arbitrary cosmic ray spectral index is related to the special case of magnetic field index $\gamma =2$ in agreement with the analytical formulae provided by Lazarian \& Pogosyan (2012); (2) the anisotropy of synchrotron total and polarization intensities arising from Alfvén and slow modes increases with the increase of the viewing angle, while that of fast mode remains almost unchanged with the viewing angle; (3) the analytical formulae of synchrotron intensities for studying turbulence can be applied to describing statistics of polarization intensities, and the QM can be successfully used to recover turbulence anisotropy. This study validates Lazarian \& Pogosyan's analytical approach and opens a way to study turbulence from observations.

Accepted by ApJ. 15 pages, 9 figures and 1 Table

References in corpus (27)

• Theory of Star Formation
• Revised equipartition & minimum energy formula for magnetic field strength estimates from radio synchrotron observations
• The Vertical Structure of Warm Ionised Gas in the Milky Way
• The outer scale of turbulence in the magneto-ionized Galactic interstellar medium
• Cosmic Ray Propagation: Nonlinear Diffusion Parallel and Perpendicular to Mean Magnetic Field
• 3D Turbulent Reconnection: Theory, Tests and Astrophysical Implications
• Velocity centroids as tracers of the turbulent velocity statistics
• Velocity Gradients as a Tracer for Magnetic Fields
• Tracing interstellar magnetic field using velocity gradient technique: Application to Atomic Hydrogen data
• Diffusion of cosmic rays in MHD turbulence with magnetic mirrors
• MHD Turbulence
• Turbulence Spectra from Spectral Lines: Tests of the Velocity Channel Analysis and Velocity Coordinate Spectrum Techniques
• Magnetic fields in the Milky Way from pulsar observations: effect of the correlation between thermal electrons and magnetic fields
• Study of velocity centroids based on the theory of fluctuations in position-position-velocity space
• Magnetic field strength from turbulence theory (I): Using differential measure approach (DMA)
• Through thick or thin: Multiple components of the magneto-ionic medium towards the nearby $\mathrm{H}\mathrm{II}$ region Sharpless 2-27 revealed by Faraday tomography
• Polarimetric studies of magnetic turbulence with interferometer
• The Global Magneto-Ionic Medium Survey: A Faraday Depth Survey of the Northern Sky Covering 1280-1750 MHz
• Anisotropic Turbulence in Position-Position-Velocity Space: Probing Three-Dimensional Magnetic Fields
• Faraday tomography of LoTSS-DR2 data: I. Faraday moments in the high-latitude outer Galaxy and revealing Loop III in polarisation
• Tracing magnetic fields by the synergies of synchrotron emission gradients
• Tracing Magnetic Field with Synchrotron Polarization Gradients: Parameter Study
• Studying the local magnetic field and anisotropy of magnetic turbulence by synchrotron polarization derivative
• Advanced Diagnostics for the Study of Linearly Polarized Emission. I: Derivation
• Studying Anisotropy of Compressible Magnetohydrodynamic Turbulence by Synchrotron Polarization Intensity
• Can Turbulence Dominate Depolarization of Optical Blazars?
• Gradient measurement of synchrotron polarization diagnostic: Application to spatially separated emission and Faraday rotation regions

Cited by in corpus (2)

• Exploring the intermittency of magnetohydrodynamic turbulence by synchrotron polarization radiation
• Measurement of the scaling slope of compressible magnetohydrodynamic turbulence by synchrotron radiation statistics