The JCMT BISTRO-2 Survey: Magnetic Fields of the Massive DR21 Filament
Authors: Ching Tao-Chung , Qiu Keping , Li Di , Ren Zhiyuan , Lai Shih-Ping , Berry David , Pattle Kate , Furuya Ray , Ward-Thompson Derek , Johnstone Doug , Koch Patrick M. , Lee Chang Won , Hoang Thiem , Hasegawa Tetsuo , Kwon Woojin , Bastien Pierre , Eswaraiah Chakali , Wang Jia-Wei , Kim Kyoung Hee , Hwang Jihye , Soam Archana , Lyo A-Ran , Liu Junhao , Le Gouellec Valentin J. M. , Arzoumanian Doris , Whitworth Anthony , Francesco James Di , Poidevin Frédérick , Liu Tie , Coudé Simon , Tahani Mehrnoosh , Liu Hong-Li , Onaka Takashi , Li Dalei , Tamura Motohide , Chen Zhiwei , Tang Xindi , Kirchschlager Florian , Bourke Tyler L. , Byun Do-Young , Chen Mike , Chen Huei-Ru Vivien , Chen Wen Ping , Cho Jungyeon , Choi Yunhee , Choi Youngwoo , Choi Minho , Chrysostomou Antonio , Chung Eun Jung , Dai Y. Sophia , Diep Pham Ngoc , Doi Yasuo , Duan Yan , Duan Hao-Yuan , Eden David , Fanciullo Lapo , Fiege Jason , Fissel Laura M. , Franzmann Erica , Friberg Per , Friesen Rachel , Fuller Gary , Gledhill Tim , Graves Sarah , Greaves Jane , Griffin Matt , Gu Qilao , Han Ilseung , Hayashi Saeko , Houde Martin , Hull Charles L. H. , Inoue Tsuyoshi , Inutsuka Shu-ichiro , Iwasaki Kazunari , Jeong Il-Gyo , Könyves Vera , Kang Ji-hyun , Kang Miju , Karoly Janik , Kataoka Akimasa , Kawabata Koji , Kemper Francisca , Kim Jongsoo , Kim Mi-Ryang , Kim Shinyoung , Kim Hyosung , Kim Kee-Tae , Kim Gwanjeong , Kirk Jason , Kobayashi Masato I. N. , Kusune Takayoshi , Kwon Jungmi , Lacaille Kevin , Law Chi-Yan , Lee Sang-Sung , Lee Hyeseung , Lee Jeong-Eun , Lee Chin-Fei , Lee Yong-Hee , Li Guangxing , Li Hua-bai , Lin Sheng-Jun , Liu Sheng-Yuan , Lu Xing , Mairs Steve , Matsumura Masafumi , Matthews Brenda , Moriarty-Schieven Gerald , Nagata Tetsuya , Nakamura Fumitaka , Nakanishi Hiroyuki , Ngoc Nguyen Bich , Ohashi Nagayoshi , Park Geumsook , Parsons Harriet , Peretto Nicolas , Priestley Felix , Pyo Tae-Soo , Qian Lei , Rao Ramprasad , Rawlings Mark , Rawlings Jonathan , Retter Brendan , Richer John , Rigby Andrew , Sadavoy Sarah , Saito Hiro , Savini Giorgio , Seta Masumichi , Shimajiri Yoshito , Shinnaga Hiroko , Tang Ya-Wen , Tomisaka Kohji , Tram Le Ngoc , Tsukamoto Yusuke , Viti Serena , Wang Hongchi , Wu Jintai , Xie Jinjin , Yang Meng-Zhe , Yen Hsi-Wei , Yoo Hyunju , Yuan Jinghua , Yun Hyeong-Sik , Zenko Tetsuya , Zhang Chuan-Peng , Zhang Yapeng , Zhang Guoyin , Zhou Jianjun , Zhu Lei , de Looze Ilse , André Philippe , Dowell C. Darren , Eyres Stewart , Falle Sam , Robitaille Jean-François , van Loo Sven 
Published: December 2022

Abstract
We present 850 μm dust polarization observations of the massive DR21 filament from the B-fields In STar-forming Region Observations (BISTRO) survey, using the POL-2 polarimeter and the SCUBA-2 camera on the James Clerk Maxwell Telescope. We detect ordered magnetic fields perpendicular to the parsec-scale ridge of the DR21 main filament. In the subfilaments, the magnetic fields are mainly parallel to the filamentary structures and smoothly connect to the magnetic fields of the main filament. We compare the POL-2 and Planck dust polarization observations to study the magnetic field structures of the DR21 filament on 0.1–10 pc scales. The magnetic fields revealed in the Planck data are well-aligned with those of the POL-2 data, indicating a smooth variation of magnetic fields from large to small scales. The plane-of-sky magnetic field strengths derived from angular dispersion functions of dust polarization are 0.6–1.0 mG in the DR21 filament and ∼0.1 mG in the surrounding ambient gas. The mass-to-flux ratios are found to be magnetically supercritical in the filament and slightly subcritical to nearly critical in the ambient gas. The alignment between column density structures and magnetic fields changes from random alignment in the low-density ambient gas probed by Planck to mostly perpendicular in the high-density main filament probed by James Clerk Maxwell Telescope. The magnetic field structures of the DR21 filament are in agreement with MHD simulations of a strongly magnetized medium, suggesting that magnetic fields play an important role in shaping the DR21 main filament and subfilaments.