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
Journal
Astrophysical Journal
Publisher
American Astronomical Society / IOP Publishing
Publisher DOI
Abstract
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
Faculty of Environment, Science and Economy
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