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Journal Paper

전체
JCMT BISTRO Survey: Magnetic Fields within the Hub-filament Structure in IC 5146 SCI
  • Jia-Wei Wang;Shih-Ping Lai;Chakali Eswaraiah;Tie Liu;Archana Soam;Kee-Tae Kim;Chang Won Lee;Thiem Hoang;Jihye Hwang;Woojin Kwon;Do-Young Byun;Choi, Minho;Chung, Eun Jung;Han, Ilseung;Jeong, Il-Gyo;Ji-hyun Kang;Kang, Miju;Kang, Sung-Ju;KIM, JONGSOO;Kim, Mi-Ryang;Shinyoung Kim;Lee Sang-Sung;A-RAN LYO;Park, Geumsook;Hyunju Yoo;Lei Zhu
  • 2019-05-01
  • ASTROPHYSICAL JOURNAL 876 1 : 42-1~42-19
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 Alfvenic 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.