The mean plane-of-sky magnetic field strength is traditionally obtained from the combination of polarization and spectroscopic data using Davis-Chandrasekhar-Fermi (DCF) technique. However, we identify major problem DCF to be its disregard anisotropic character MHD turbulence. On basis modern turbulence theory introduce a new way obtaining observations. Unlike DCF, technique uses not dispersion angle line sight velocities, but increments these quantities given by structure functions. To...

Abstract Plasma turbulence is a ubiquitous dynamical process that transfers energy across many spatial and temporal scales affects energetic particle transport. Recent advances in the understanding of compressible magnetohydrodynamic (MHD) demonstrate important role damping shaping distributions on small scales, yet its observational evidence still lacking. This study provides first substantial collisionless (CD) modulation small-amplitude MHD cascade Earth’s magnetosheath using four Cluster...

We describe a new technique for probing galactic and extragalactic 2D 3D magnetic field distribution using gradients of polarized synchrotron emission. The fluctuations are elongated along the ambient field. Therefore, variations maximal perpendicular to B-field. This allows tracing B-field with polarization (SPGs). demonstrate that Faraday depolarization map structure by. ensures sample regions close observer sampling depth controlled by frequency radiation. also analyze properties...

Abstract We identify velocity channel map intensities as a new way to trace magnetic fields in turbulent media. This work makes use of both the modern theory magnetohydrodynamic (MHD) turbulence, which predicts that eddies are aligned with local direction field, and also spectral line position–position–velocity (PPV) statistics, describes how density fluctuations mapped onto PPV space. In particular, we fact intensity thin maps mostly affected by velocity, while thick dominated variations....

Abstract Plasma turbulence is a ubiquitous dynamical process that transfers energy across many spatial and temporal scales in astrophysical space plasma systems. Although the theory of anisotropic magnetohydrodynamic (MHD) has successfully described natural phenomena, its core prediction an Alfvénic transition from weak to strong MHD when cascades large small not been observationally confirmed. Here we report evidence for weak-to-strong small-amplitude, turbulent fluctuations Earth’s...

The advancement of our understanding MHD turbulence opens ways to develop new techniques probe magnetic fields. In turbulence, the velocity gradients are expected be perpendicular fields and this fact was used by Gonsalvez-Casanova & Lazarian introduce a technique trace using centroid gradients. latter can obtained from spectroscopic observations. We apply GALFA HI survey data compare directions with direction PLANCK polarization. find excellent correspondence between two field tracing,...

Abstract On the basis of modern understanding MHD turbulence, we propose a new way using synchrotron radiation: intensity gradients (SIGs) for tracing astrophysical magnetic fields. We successfully test technique synthetic data obtained with 3D simulations and provide demonstration practical utility by comparing directions fields that are PLANCK to polarization data. demonstrate SIGs can reliably trace in presence noise detailed maps field directions. also show relatively robust while low...

Tracing of the magnetic field with Velocity Gradient Technique (VGT) allows observers to probe directions spectroscopic data. In this paper, we employ method principal component analysis (PCA) extract information most valuable for VGT. By using synthetic observation data from numerical simulations, show that PCA acts in a way similar spatial filtering along velocity axis. We study both subsonic and supersonic simulations tracing fields by VGT is significantly improved. Using 21 cm Galactic...

Abstract Magnetic fields are ubiquitous in the interstellar medium but notoriously difficult to study through observation. Making use of advances our understanding MHD turbulence and turbulent reconnection, velocity gradients technique (VGT) was suggested successfully applied magnetic utilizing spectroscopic data. Applying tools developed for VGT intensity statistics, we introduce (IGT) as a complementary tool that can be used synergistically with VGT. In this paper, apply IGT diffuse H i...

Abstract Understanding how star formation is regulated requires studying the energy balance between turbulence, magnetic fields, stellar feedback, and gravity within molecular clouds. However, identifying transition region where takes over remains elusive. Recent studies of Velocity Gradient Technique (VGT), which an advanced tool for field studies, reveal that gradients spectroscopic observables change their directions by 90° with respect to fields in regions gravitational collapse. In this...

Alfven wave is the single most important physical phenomenon of magneto-hydrodynamic turbulence and has far-reaching impact to almost all studies related astrophysical magnetic field. Yet restoration fluctuations from a given field, aka local problem, never properly addressed in literature albeit its importance. Previous works model fluctuation as perturbation along straight-line, constant However, Lazarian & Pogosyan (2012) suggested that decomposition straight line, aka. global frame...

ABSTRACT Magnetic fields are crucial in numerous astrophysical processes within the interstellar medium (ISM). However, detailed determination of magnetic field geometry is notoriously challenging. Based on modern magnetohydrodynamic (MHD) turbulence theory, we introduce a novel statistical technique, ‘Y-parameter’, to decipher inclination ISM and identify dominant modes. The Y-parameter, calculated as ratio anisotropies different Stokes parameter combinations, displays contrasting trends...

Abstract Magnetic fields are ubiquitous in the interstellar medium, including extended objects such as supernova remnants and diffuse halos around pulsars. Its turbulent characteristics govern diffusion of cosmic rays multiwavelength emission from pulsar wind nebulae (PWNe). However, geometry turbulence nature magnetic ambient region PWN is still unknown. Recent gamma-ray observations HAWC synchrotron suggest a highly suppressed coefficient compared to mean value. In this study, we present...

Abstract The gradient technique is a promising tool with theoretical foundations based on the fundamental properties of MHD turbulence and turbulent reconnection. Its various incarnations use spectroscopic, synchrotron, intensity data to trace magnetic field measure media magnetization in terms Alfvén Mach number. We provide an analytical theory measurements quantify effects averaging gradients along line sight over plane sky. derive expressions that relate distribution number M A . show...

This study proceeds with the development of technique employing velocity gradients that were identified in (\cite{GL17}, henceforth GL17) as a means probing magnetic field interstellar media. We demonstrate number practical ways on improving accuracy tracing fields diffuse media using centroid (VCGs). Addressing super-Alfvenic turbulence we introduce procedure filtering low spatial frequencies, enables situations when kinetic energy turbulent plasmas dominate its energy. propose synergic way...

Abstract Recent developments of the velocity gradient technique (VGT) show that gradients provide a reliable tracing magnetic field direction in turbulent plasmas. In this paper, we explore ability to measure magnetization interstellar medium. We demonstrate distribution orientations provides estimation media. particular, determine relation between Alfvénic Mach number M A range <?CDATA ${M}_{{\rm{A}}}\in [0.2,1.7]$?> and properties distribution, namely, with dispersion orientation as well...

Probing magnetic fields in Giant Molecular Clouds is often challenging. Fortunately, recently simulations show that analysis of velocity gradients (the Velocity Gradient Technique) can be used to map out the field morphology different physical layers within molecular clouds when applied CO isotopologues with optical depths. Here, we test effectiveness Technique reconstructing structure cloud Vela C, employing seven chemical tracers have depths, i.e. 12CO, 13CO, C18O, CS, HNC, HCO+, and HCN....

Abstract Observations of fluctuations in the cosmic microwave background provide information about primordial inhomogeneities universe. However, B-mode polarization inflationary gravitational wave is contaminated by Galactic foreground polarized radiation arising from dust aligned interstellar magnetic fields. To trace fields, we use Velocity Gradient Technique (VGT), which employs modern understanding nature magnetohydrodynamic turbulent motions. In this paper, combine VGT with Principal...

ABSTRACT The ubiquity of very thin and lengthy cold neutral medium (CNM) has been reported by multiple authors in the H i community. Yet, reason how CNM can be so long is still debate. In this paper, we recognize a new type instability due to attractive nature pressure force unstable phase. We provide estimation average filament aspect ratio with consideration balances at phase boundary, which roughly 5–20 common environment. show that most filaments are less filamentary than what usually...

Magnetohydrodynamic(MHD) turbulence displays velocity anisotropies which reflect the direction of magnetic field. This anisotropy has led to development a number statistical techniques for studying fields in interstellar medium. In this paper, we review and compare three that use radio position-position-velocity data determining field strength morphology : correlation function (CFA), Principal Component Analysis Anisotropies (PCAA), more recent Velocity Gradient Technique (VGT). We these...

Abstract The recent development of the velocity gradient technique allows observers to map magnetic field orientations and magnetization using direction gradients. Aside from directions, amplitudes gradients also contain valuable information about underlying properties magnetohydrodynamic (MHD) turbulence. In this paper, we explore what physical is contained in discuss how can be used diagnose turbulence both diffuse self-gravitating interstellar media. We identify relations between...

A recent publication by Clark et.al (2019, CX19) uses both GALFA-HI observational data and numerical simulations to address the nature of intensity fluctuations in Position-Position-Velocity (PPV) space. The study questions validity applicability statistical theory PPV space formulated Lazarian &amp; Pogosyan (2000, LP00) HI gas concludes that $"${\it a significant reassessment many theoretical studies turbulence HI}$"$. This implies dozens papers used LP00 explore interstellar as well...