Wang, Jia-Wei, Lai, Shih-Ping, Eswaraiah, Chakali, Pattle, Kate, Francesco, James Di, Johnstone, Doug, Koch, Patrick M., Liu, Tie, Tamura, Motohide, Furuya, Ray S., Onaka, Takashi, Ward-Thompson, Derek, Soam, Archana, Kim, Kee-Tae, Lee, Chang Won, Lee, Chin-Fei, Mairs, Steve, Arzoumanian, Doris, Kim, Gwanjeong, Hoang, Thiem, Hwang, Jihye, Liu, Sheng-Yuan, Berry, David, Bastien, Pierre, Hasegawa, Tetsuo, Kwon, Woojin, Qiu, Keping, André, Philippe, Aso, Yusuke, Byun, Do-Young, Chen, Huei-Ru, Chen, Michael C., Chen, Wen Ping, Ching, Tao-Chung, Cho, Jungyeon, Choi, Minho, Chrysostomou, Antonio, Chung, Eun Jung, Coudé, Simon, Doi, Yasuo, Dowell, C. Darren, Drabek-Maunder, Emily ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
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Abstract
We present the 850 μm polarization observations toward the IC 5146 filamentary cloud taken using the Submillimetre Common-User Bolometer Array 2 (SCUBA-2) and its associated polarimeter (POL-2), mounted on the James Clerk Maxwell Telescope, as part of the B-fields In STar forming Regions Observations. This work is aimed at revealing the magnetic field morphology within a core-scale (lesssim1.0 pc) hub-filament structure (HFS) located at the end of a parsec-scale filament. To investigate whether the observed polarization traces the magnetic field in the HFS, we analyze the dependence between the observed polarization fraction and total intensity using a Bayesian approach with the polarization fraction described by the Rice likelihood function, which can correctly describe the probability density function of the observed polarization fraction for low signal-to-noise ratio data. We find a power-law dependence between the polarization fraction and total intensity with an index of 0.56 in A V ~ 20–300 mag regions, suggesting that the dust grains in these dense regions can still be aligned with magnetic fields in the IC 5146 regions. Our polarization maps reveal a curved magnetic field, possibly dragged by the contraction along the parsec-scale filament. We further obtain a magnetic field strength of 0.5 ± 0.2 mG toward the central hub using the Davis–Chandrasekhar–Fermi method, corresponding to a mass-to-flux criticality of ~1.3 ± 0.4 and an Alfvénic Mach number of <0.6. These results suggest that gravity and magnetic field are currently of comparable importance in the HFS and that turbulence is less important.
Item Type: | Article |
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Date Type: | Publication |
Status: | Published |
Schools: | Physics and Astronomy |
Publisher: | American Astronomical Society |
ISSN: | 0004-637X |
Date of First Compliant Deposit: | 14 May 2019 |
Date of Acceptance: | 25 March 2019 |
Last Modified: | 05 Dec 2023 02:49 |
URI: | https://orca.cardiff.ac.uk/id/eprint/122434 |
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