Mapping the magnetic field in the Taurus/B211 filamentary cloud with SOFIA HAWC+ and comparing with simulation

Abstract

Optical and infrared polarization mapping and recent Planck observations of the filamentary cloud L1495 in Taurus show that the large-scale magnetic field is approximately perpendicular to the long axis of the cloud. We use the HAWC+ polarimeter on SOFIA to probe the complex magnetic field in the B211 part of the cloud. Our results reveal a dispersion of polarization angles of $36^{\circ }$, about five times that measured on a larger scale by Planck. Applying the Davis-Chandrasekhar-Fermi (DCF) method with velocity information obtained from IRAM 30m C${}^{18}$O(1-0) observations, we find two distinct sub-regions with magnetic field strengths differing by more than a factor 3. The quieter sub-region is magnetically critical and sub-Alfvénic; the field is comparable to the average field measured in molecular clumps based on Zeeman observations. The more chaotic, super-Alfvénic sub-region shows at least three velocity components, indicating interaction among multiple substructures. Its field is much less than the average Zeeman field in molecular clumps, suggesting that the DCF value of the field there may be an underestimate. Numerical simulation of filamentary cloud formation shows that filamentary substructures can strongly perturb the magnetic field. DCF and true field values in the simulation are compared. Pre-stellar cores are observed in B211 and are seen in our simulation. The appendices give a derivation of the standard DCF method that allows for a dispersion in polarization angles that is not small, present an alternate derivation of the structure function version of the DCF method, and treat fragmentation of filaments.

27 pages, 12 figures

References in corpus (14)

• Theory of Star Formation
• Cold Dark Clouds: The Initial Conditions for Star Formation
• Studies of regular and random magnetic fields in the ISM: statistics of polarization vectors and the Chandrasekhar-Fermi technique
• The Fragmentation of Magnetized, Massive Star-Forming Cores with Radiative Feedback
• Chains of dense cores in the Taurus L1495/B213 complex
• Magnetically Aligned Velocity Anisotropy in the Taurus Molecular Cloud
• High-accuracy estimation of magnetic field strength in the interstellar medium from dust polarization
• JCMT POL-2 and BISTRO Survey observations of magnetic fields in the L1689 molecular cloud
• Magnetized interstellar molecular clouds: II. The Large-Scale Structure and Dynamics of Filamentary Molecular Clouds
• Magnetic Properties of Star-Forming Dense Cores
• Revealing the diverse magnetic field morphologies in Taurus dense cores with sensitive sub-millimeter polarimetry
• ALMA reveals the magnetic field evolution in the high-mass star forming complex G9.62+0.19
• The Magnetic Field Across the Molecular Warped Disk of Centaurus A
• Magnetohydrostatic Equilibrium Structure and Mass of Polytropic Filamentary Cloud Threaded by Lateral Magnetic Field

Cited by in corpus (21)

• On the typical width of Herschel filaments
• Magnetic field properties in star formation: a review of their analysis methods and interpretation
• Magnetic field strength from turbulence theory (I): Using differential measure approach (DMA)
• The Davis-Chandrasekhar-Fermi Method Revisited
• Extragalactic magnetism with SOFIA (SALSA Legacy Program) -- III: First data release and on-the-fly polarization mapping characterization
• SOFIA observations of 30 Doradus: II -- Magnetic fields and large scale gas kinematics
• The Magnetic Field in the Milky Way Filamentary Bone G47
• Nature of Striation in 21 cm Channel Maps: Velocity Caustics
• Energy balance and Alfvén Mach numbers in compressible magnetohydrodynamic turbulence with a large-scale magnetic field
• Mapping the Galactic Magnetic Field Orientation and Strength in Three Dimensions
• Probing Three-Dimensional Magnetic Fields: I -- Polarized Dust Emission
• Alignment of dense molecular core morphology and velocity gradients with ambient magnetic fields
• Increasing mass-to-flux ratio from the dense core to the protostellar envelope around the Class 0 protostar HH 211
• The Role of Magnetic Fields in the Stability and Fragmentation of Filamentary Molecular Clouds: Two Case Studies at OMC-3 and OMC-4
• On the origin of radio-loudness in active galactic nuclei using far-infrared polarimetric observations
• The Role of Magnetic Fields in the Formation of the Filamentary Infrared Dark Cloud G11.11-0.12
• The origin of dust polarization in the Orion Bar
• Far-infrared Polarization of the Supernova Remnant Cassiopeia A with SOFIA HAWC+
• Obtaining strength of magnetic field from E and B modes of dust polarization
• Description of turbulent dynamics in the interstellar medium: Multifractal microcanonical analysis: II. Sparse filtering of Herschel observation maps and visualization of filamentary structures at different length scales
• Modeling the Far-Infrared Polarization Spectrum of a High-Mass Star Forming Cloud