Interpreting the Role of the Magnetic Field from Dust Polarization Maps

Дата и время публикации : 2013-08-28T15:24:35Z

Авторы публикации и институты :
Patrick M. Koch
Ya-Wen Tang
Paul T. P. Ho

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: 53 pages, 23 figures, 3 tables; accepted for publication in ApJ
Первичная категория: astro-ph.GA

Все категории : astro-ph.GA

Краткий обзор статьи: Dust polarization observations from the Submillimeter Array (SMA) and the Caltech Submillimeter Observatory (CSO) are analyzed with the goal of providing a general tool to interpret the role of the magnetic field in molecular clouds. Magnetic field and dust emission gradient orientations are observed to show distinct patterns and features. The angle $delta$ between these two orientations can be interpreted as a magnetic field alignment deviation, assuming the emission gradient orientation to coincide with the density gradient orientation in the magnetohydrodynamics (MHD) force equation. In SMA high-resolution (collapsing) cores, additional symmetry properties in $delta$ can reveal accretion and outflow zones. All these observational findings suggest the angle $delta$ to be a relevant quantity that can assess the role of the magnetic field. Indeed, when comparing this angle with the (projection-free) magnetic field significance Sigma_B (Koch et al. 2012a), it is demonstrated that |delta| yields an approximation to the change in Sigma_B. Thus, changes in the magnetic field alignment deviation $delta$ trace changes in the role of the magnetic field. The angle $delta$ is observationally straightforward to determine, providing a tool to distinguish between zones of minor or significant magnetic field impact. This is exemplified by the CSO M+0.25+0.01, Mon R2, CO+0.02-0.02, M-0.02-0.07 sources and by the SMA high-resolution data from W51 e2, W51 North, Orion BN/KL and g5.89. Additional CSO sources are analyzed, providing further support of this result. Finally, based on the different features found in our sample of 31 sources in total, covering sizes from large-scale complexes to collapsing cores, a schematic evolutionary scenario is proposed (abridged).

Category: Physics