Anisotropies in Compressible MHD Turbulence: Probing Magnetic Fields and Measuring Magnetization

Abstract

Probing magnetic fields in the interstellar medium (ISM) is notoriously challenging. Motivated by the modern theories of magnetohydrodynamic (MHD) turbulence and turbulence anisotropy, we introduce the Structure-Function Analysis (SFA) as a new approach to measure the magnetic field orientation and estimate the magnetization. We analyze the statistics of turbulent velocities in three-dimensional compressible MHD simulations through the second-order structure functions in both local and global reference frames. In the sub-Alfvenic turbulence with the magnetic energy larger than the turbulent energy, the SFA of turbulent velocities measured in the directions perpendicular and parallel to the magnetic field can be significantly different. Their ratio has a power-law dependence on the Alfven Mach number $M_A$, which is inversely proportional to the magnetic field strength. We demonstrate that the anisotropic structure functions of turbulent velocities can be used to estimate both the orientation and strength of magnetic fields. With turbulent velocities measured using different tracers, our approach can be generally applied to probing the magnetic fields in the multi-phase interstellar medium.

12 pages, 6 figures, accepted for publication in ApJ

References in corpus (30)

• The Gaia mission
• Theory of Star Formation
• Tracing Magnetic Fields with Aligned Grains
• Density Fluctuations in MHD Turbulence: Spectra, Intermittency and Topology
• Studies of regular and random magnetic fields in the ISM: statistics of polarization vectors and the Chandrasekhar-Fermi technique
• 3D Turbulent Reconnection: Theory, Tests and Astrophysical Implications
• Estimating extragalactic Faraday rotation
• Deep 1.4 GHz VLA Observations of the Radio Halo and Relic in Abell 2256
• Magnetically Aligned Velocity Anisotropy in the Taurus Molecular Cloud
• The Turbulent Warm Ionized Medium: Emission Measure Distribution and MHD Simulations
• The Southern Galactic Plane Survey: Polarized Radio Continuum Observations and Analysis
• Velocity centroids as tracers of the turbulent velocity statistics
• Velocity Gradients as a Tracer for Magnetic Fields
• Subsonic Mechanical Alignment of Irregular Grains
• Tracing interstellar magnetic field using velocity gradient technique: Application to Atomic Hydrogen data
• Probing the Turbulence Dissipation Range and Magnetic Field Strengths in Molecular Clouds
• Turbulent dynamo in a conducting fluid and partially ionized gas
• Direct Detection of Black Hole-Driven Turbulence in the Centers of Galaxy Clusters
• Magnetic Field Morphology in Interstellar Clouds with the Velocity Gradient Technique
• The Physical Nature of Neutral Hydrogen Intensity Structure
• Measuring the Alfvenic Nature of the Interstellar Medium: Velocity Anisotropy Revisited
• Study of velocity centroids based on the theory of fluctuations in position-position-velocity space
• Revealing Gravitational Collapse in Serpens G3-G6 Molecular Cloud using Velocity Gradients
• Extracting the cold neutral medium from HI emission with deep learning: Implications for Galactic foregrounds at high latitude
• Measuring Turbulence with Young Stars in the Orion Complex
• Anisotropies in the HI gas distribution toward 3C196
• Predictions of Cosmic Microwave Background Foregrounds Dust Polarization Using Velocity Gradients
• Measuring magnetization with rotation measures and velocity centroids in supersonic MHD turbulence
• Obtaining magnetic field strength using differential measure approach and velocity channel maps
• Bow Magnetic Morphology Surrounding Filamentary Molecular Clouds? 3D Magnetic Field Structure of Orion-A

Cited by in corpus (16)

• Superdiffusion of Cosmic Rays in Compressible Magnetized Turbulence
• Magnetic field strength from turbulence theory (I): Using differential measure approach (DMA)
• Revealing Gravitational Collapse in Serpens G3-G6 Molecular Cloud using Velocity Gradients
• The Velocity Statistics of Turbulent Clouds in the Presence of Gravity, Magnetic fields, Radiation, and Outflow Feedback
• Role of magnetic fields in fueling Seyfert nuclei
• Synchrotron Intensity Gradient Revealing Magnetic Fields in Galaxy Clusters
• Anisotropic Turbulence in Position-Position-Velocity Space: Probing Three-Dimensional Magnetic Fields
• Mirror diffusion of cosmic rays in highly compressible turbulence near supernova remnants
• Probing Three-Dimensional Magnetic Fields: I -- Polarized Dust Emission
• Decomposing Magnetic Fields in Three Dimensions over the Central Molecular Zone
• Mapping the Galactic Magnetic Field Orientation and Strength in Three Dimensions
• Multi-Phase Magnetic Fields in the Galaxy NGC 3627
• Characterizing three-dimensional magnetic field, turbulence, and self-gravity in the star-forming region L1688
• Three-dimensional magnetic fields of molecular clouds
• Parallel and Perpendicular Alignments of Velocity Gradient and Magnetic Field observed in the Molecular Clouds L1478 and L1482
• Turbulence Mode Decomposition and Anisotropy in Magnetically Dominated Collisionless Plasmas