Three-dimensional magnetic fields of molecular clouds

Tahani, Mehrnoosh

doi:10.3389/fspas.2022.940027

Cited by 4 publications

(4 citation statements)

References 138 publications

(183 reference statements)

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“…These cloudformation models often result in an arc-shaped (bow-shaped) magnetic field morphology (Heiles 1997;Tahani et al 2019Tahani et al , 2022aTahani et al , 2022b) that may appear perpendicular to the cloud when projected onto the plane of the sky. The shockcloud interaction model is also supported in other regions by line-of-sight (Tahani et al 2018(Tahani et al , 2020 and 3D (Tahani et al 2019(Tahani et al , 2022a(Tahani et al , 2022bTahani 2022) magnetic field and velocity (Arzoumanian et al 2018;Bonne et al 2020) observations.…”

Section: Cloud and Magnetic Field Coevolutionmentioning

confidence: 72%

JCMT BISTRO Observations: Magnetic Field Morphology of Bubbles Associated with NGC 6334

Tahani

Bastien

Furuya

et al. 2023

ApJ

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We study the Hii regions associated with the NGC 6334 molecular cloud observed in the submillimeter and taken as part of the B-fields In STar-forming Region Observations Survey. In particular, we investigate the polarization patterns and magnetic field morphologies associated with these Hii regions. Through polarization pattern and pressure calculation analyses, several of these bubbles indicate that the gas and magnetic field lines have been pushed away from the bubble, toward an almost tangential (to the bubble) magnetic field morphology. In the densest part of NGC 6334, where the magnetic field morphology is similar to an hourglass, the polarization observations do not exhibit observable impact from Hii regions. We detect two nested radial polarization patterns in a bubble to the south of NGC 6334 that correspond to the previously observed bipolar structure in this bubble. Finally, using the results of this study, we present steps (incorporating computer vision; circular Hough transform) that can be used in future studies to identify bubbles that have physically impacted magnetic field lines.

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Section: Cloud and Magnetic Field Coevolutionmentioning

confidence: 72%

JCMT BISTRO Observations: Magnetic Field Morphology of Bubbles Associated with NGC 6334

Tahani

Bastien

Furuya

et al. 2023

ApJ

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“…This hints that the same scenario might be at the origin of filament formation in both a low-and high-mass starforming region. Furthermore, recent magnetic field and velocity observations of some nearby low-and high-mass star-forming regions (e.g., Arzoumanian et al 2022;Tahani 2022) appear to have a straightforward explanation in this scenario. This leads us to tentatively propose that these types of collisions are a widespread mechanism in the Milky Way to initiate a wide variety of star formation activity in the Milky Way.…”

Section: Discussionmentioning

confidence: 94%

Unveiling the Formation of the Massive DR21 Ridge

Bonne

Bontemps

Schneider

et al. 2023

ApJ

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We present new 13CO (1−0), C18O (1−0), HCO+ (1−0), and H13CO+ (1−0) maps from the IRAM 30 m telescope and a spectrally resolved [C ii] 158 μm map observed with the SOFIA telescope toward the massive DR21 cloud. This traces the kinematics from low- to high-density gas in the cloud, which allows us to constrain the formation scenario of the high-mass star-forming DR21 ridge. The molecular line data reveal that the subfilaments are systematically redshifted relative to the dense ridge. We demonstrate that [C ii] unveils the surrounding CO-poor gas of the dense filaments in the DR21 cloud. We also show that this surrounding gas is organized in a flattened cloud with curved redshifted dynamics perpendicular to the ridge. The subfilaments thus form in this curved and flattened mass reservoir. A virial analysis of the different lines indicates that self-gravity should drive the evolution of the ridge and surrounding cloud. Combining all results, we propose that bending of the magnetic field, due to the interaction with a mostly atomic colliding cloud, explains the velocity field and resulting mass accretion on the ridge. This is remarkably similar to what was found for at least two nearby low-mass filaments. We tentatively propose that this scenario might be a widespread mechanism to initiate star formation in the Milky Way. However, in contrast to low-mass clouds, gravitational collapse plays a role on the parsec scale of the DR21 ridge because of the higher density. This allows more effective mass collection at the centers of collapse and should facilitate massive cluster formation.

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“…In addition, the combination of our method using dust polarization with other B-field measurement techniques can further support probing both B-field and dust properties in starforming regions. For instance, the Faraday rotation method (see, e.g., Tahani et al 2018;Tahani 2022) can trace the orientation of B-fields pointing toward or away from us. By combining with our method using dust polarization, we can reconstruct both the morphology and directions of 3D B-fields, particularly in molecular clouds.…”

Section: Constraining 3d B-fields With Dust Polarizationmentioning

confidence: 99%

Probing 3D Magnetic Fields Using Thermal Dust Polarization and Grain Alignment Theory

Hoang,

Truong

2024

ApJ

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Magnetic fields are ubiquitous in the Universe and are thought to play an important role in various astrophysical processes. Polarization of thermal emission from dust grains aligned with the magnetic field is widely used to measure the 2D magnetic field projected onto the plane of the sky, but its component along the line of sight is not yet constrained. Here, we introduce a new method to infer 3D magnetic fields using thermal dust polarization and grain alignment physics. We first develop a physical model of thermal dust polarization using the modern grain alignment theory based on the magnetically enhanced radiative torque alignment theory. We then test this model with synthetic observations of magnetohydrodynamic simulations of a filamentary cloud with our updated POLARIS code. Combining the tested physical polarization model with synthetic polarization, we show that the B-field inclination angles can be accurately constrained by the polarization degree from synthetic observations. Compared to the true 3D magnetic fields, our method based on grain alignment physics is more accurate than the previous methods that assume uniform grain alignment. This new technique paves the way for tracing 3D B-fields using thermal dust polarization and grain alignment theory and for constraining dust properties and grain alignment physics.

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Three-dimensional magnetic fields of molecular clouds

Cited by 4 publications

References 138 publications

JCMT BISTRO Observations: Magnetic Field Morphology of Bubbles Associated with NGC 6334

JCMT BISTRO Observations: Magnetic Field Morphology of Bubbles Associated with NGC 6334

Unveiling the Formation of the Massive DR21 Ridge

Probing 3D Magnetic Fields Using Thermal Dust Polarization and Grain Alignment Theory

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