JCMT BISTRO Survey: Magnetic Fields within the Hub-filament Structure in IC 5146

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 (≲1.0 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 AV ∼ 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.

E. Pascale | A. Scaife | P. Koch | A. Whitworth | N. Peretto | G. Fuller | H. Chen | T. Onaka | M. Tamura | Sang-Sung Lee | D. Byun | D. Johnstone | P. Bastien | Jongsoo Kim | G. Savini | J. Francesco | B. Matthews | Di Li | P. Friberg | M. Seta | J. Kwon | T. Nagata | Tsuyoshi Inoue | W. Chen | K. Kawabata | S. Eyres | S. Falle | M. Griffin | W. Holland | J. Greaves | G. Moriarty-Schieven | T. Hasegawa | D. Ward-Thompson | J. Hatchell | A. Chrysostomou | J. Fiege | R. Friesen | S. Graves | M. Houde | J. Kirk | J. Richer | P. Andr'e | K. Lacaille | C. Dowell | A. Kataoka | R. Rao | M. Rawlings | H. Parsons | Jia‐Wei Wang | L. Qian | K. Qiu | T. Ching | Jinghua Yuan | A. Rigby | Jianjun Zhou | Da-lei Li | G. Park | Miju Kang | Il-Gyo Jeong | H. Nakanishi | Jeong-Eun Lee | Kee-Tae Kim | Hongchi Wang | Tie Liu | Ji-hyun Kang | S. Inutsuka | F. Kemper | Minho Choi | Sung-ju Kang | Jungyeon Cho | H. Yoo | D. Berry | T. Pyo | F. Nakamura | S. Loo | V. Konyves | D. Arzoumanian | Guoyin Zhang | Junhao Liu | Y. Doi | J. Robitaille | Chuan-Peng Zhang | Hua-b. Li | Sheng-Yuan Liu | S. Lai | A. Soam | C. Lee | Ya-Wen Tang | Gwanjeong Kim | S. Mairs | Shinyoung Kim | K. Pattle | W. Kwon | E. Chung | A. Pon | H. Duan | S. Hayashi | M. Matsumura | Yapeng Zhang | S. Sadavoy | K. Tomisaka | Y. Tsukamoto | Hsi-Wei Yen | N. Ohashi | K. Iwasaki | Yusuke Aso | Chin-Fei Lee | H. Shinnaga | L. Fanciullo | M. C. Chen | E. Drabek-Maunder | T. Gledhill | Mi-Ryang Kim | R. Furuya | S. Coud'e | C. Eswaraiah | K. Kim | A. Lyo | B. Retter | I. Han | Hyeseung Lee | Thiem C. Hoang | Hyeong-Sik Yun | T. Zenko | Masato I. N. Kobayashi | E. Franzmann | Hong-Li Liu | Q. Gu | Yoshihiro Kanamori | H. Saito | J. Hwang | Yong-Hee Lee | Zhu | T. Inoue | S. Lai | Hongli Liu | Chuan-peng Zhang | W. Chen | H. Yun | Ya-wen Tang | Geumsook Park

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