JCMT BISTRO survey: Magnetic Fields within the Hub-Filament Structure in IC 5146
Wang, J-W; Lai, S-P; Eswaraiah, C; et al.Pattle, K; Di Francesco, J; Johnstone, D; Koch, PM; Liu, T; Tamura, M; Furuya, RS; Onaka, T; Ward-Thompson, D; Soam, A; Kim, K-T; Lee, CW; Mairs, S; Arzoumanian, D; Kim, G; Hoang, T; Hwang, J; Liu, S-Y; Berry, D; Bastien, P; Hasegawa, T; Kwon, W; Qiu, K; Andre, P; Aso, Y; Byun, D-Y; Chen, H-RV; Chen, MC; Chen, WP; Ching, T-C; Cho, J; Choi, M; Chrysostomou, A; Chung, EJ; Coudé, S; Doi, Y; Dowell, CD; Drabek-Maunder, E; Eyres, SP; Falle, S; Fanciullo, L; Fiege, J; Franzmann, E; Friberg, P; Friesen, RK; Fuller, GA; Gledhill, TM; Graves, SF; Greaves, JS; Griffin, M; Gu, Q; Hatchell, J; Hayashi, S; Holland, W; Houde, M; Inoue, T; Inutsuka, S-I; Iwasaki, K; Jeong, I-G; Kanamori, Y; Kataoka, A; Kawabata, KS; Kang, J-H; Kang, M; Kang, S-J; Kemper, F; Kim, J; Kim, KH; Kim, M-R; Kim, S; Kirk, J; Kobayashi, MI; Kwon, J; Lacaille, KM; Lee, J-E; Lee, S-S; Li, D; Li, D; Li, H-B; Liu, H; Liu, J; Lyo, A; Matsumura, M; Matthews, B; Moriarty-Schieven, GH; Nagata, T; Nakamura, F; Nakanishi, H; Ohashi, N; Parsons, HA; Peretto, N; Pon, A; Pyo, T-S; Qian, L; Rao, R; Rawlings, MG; Retter, B; Richer, J; Rigby, A; Robitaille, J-F; Sadavoy, SI; Saito, H; Savini, G; Scaife, AM; Seta, M; Shinnaga, H; Tang, Y-W; Tomisaka, K; Tsukamoto, Y; Van Loo, S; Wang, H; Whitworth, AP; Yen, H-W; Yoo, H; Yuan, J; Zenko, T; Zhang, C-P; Zhang, G; Zhou, J; Zhu, L
Date: 1 May 2019
American Astronomical Society / IOP Publishing
We present the 850 μm polarization observations toward the IC5146 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 (JCMT), as part of the B-fields In STar forming Regions Observations (BISTRO). This work is aimed ...
We present the 850 μm polarization observations toward the IC5146 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 (JCMT), as part of the B-fields In STar forming Regions Observations (BISTRO). This work is aimed at revealing the magnetic field morphology within a core-scale (≲1.0 pc) hub-filament structure (HFS) located at the end of a parsec-scale filament. To investigate whether or not 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 (PDF) of the observed polarization fraction for low signal-to-noise ratio (SNR) data. We find a power-law dependence between the polarization fraction and total intensity with an index of 0.56 in AV∼ 20--300 mag regions, suggesting that the dust grains in these dense regions can still be aligned with magnetic fields in the IC5146 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 is currently of comparable importance in the HFS, and turbulence is less important.
Physics and Astronomy
College of Engineering, Mathematics and Physical Sciences
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