Oral Presentation
Evidence of material channeled by magnetic field in the infrared dark cloud G34.43? A Comparison between Magnetic Field, Turbulence, and Gravity
Presenter: Ya-Wen Tang (ASIAA)
We investigate the interplay between magnetic field, gravity and turbulence in the fragmentation process of cores within the filamentary infrared dark cloud G34.43.
We observe the magnetic field (B) morphology across G34.43, traced with thermal dust polarization at 350 $\mu$m with an angular resolution of 10$\arcsec$ (0.06 pc), and compare with the kinematics obtained from N$_2$H$^+$ across the filament. We derive local velocity gradients from N$_{2}$H$^{+}$, tracing motion in the plane of sky, and compare with the observed local B field orientations in the plane of sky.
We find a close alignment between local B field orientations and local velocity gradients toward the MM1/MM2 ridge which appears to be anti-correlated with integrated emission. This local correlation in alignment supports a scenario where the gas motion is following the B field lines. We analyze and quantify B field, gravity, turbulence, and their relative importance toward the three cores with various techniques. MM1 is controlled by gravity which dominates over the B field which itself dominates over turbulence. MM2 reveals the strongest B field, dominating over turbulence and gravity. In MM3, gravity rules over turbulence which dominates over the weakest B field. Higher-resolution 0.02 pc observations reveal a fragmentation process that appears dramatically different in these three cores: while being clustered in MM3 and aligned in MM2, no fragmentation is resolved in MM1. We propose that the varying relative importance between B field, gravity, and turbulence on the larger scale (0.2 pc in radius) drives the different smaller-scale fragmentation types.
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