B-fields In STar-forming Region Observations (BISTRO): Technical Foundations for Quantitative 450/850 $μ$m JCMT SCUBA-2/POL-2 Polarimetry
Year: 2026
Type: preprint
Abstract: We present five technical validations of SCUBA-2/POL-2 polarimetry on the James Clerk Maxwell Telescope at 450 and 850 $μ$m, using 174 archival fields in 69 molecular cloud regions and subsets appropriate to each test. Extended-source calibration avoids a deterministic shift of $Δβ=-1.05$ in the dust emissivity index $β$ that would result from calibrating extended emission using peak brightness. We modeled Stokes $I$ noise with additive and signal-dependent components. The measured median ratio of surface-brightness noise at 450/850 $μ$m is 25. Independent tests of Stokes $Q,U$ noise support approximately equal additive variances and weak error correlations, providing a basis for propagating polarization uncertainties. Corrections determined for individual fields reduce additive zero-level offsets of order $1$ mJy arcsec$^{-2}$ in the 450 $μ$m Stokes $Q$ and $U$ intensities. The three-step regression leaves a median combined residual amplitude of $0.07$ mJy arcsec$^{-2}$. Independent comparisons with SOFIA/HAWC+ at 154 and 214 $μ$m support the correction in strongly affected fields. We matched the 450 $μ$m maps to the modeled 850 $μ$m beam and the common $12.6''$-$300''$ range of angular scales. We compared three reductions of the same 450 $μ$m observations across 30 sources. Taking the median angular residual relative to the final product for each source, we find that beam matching reduces the median over sources from $6.3^\circ$ to $4.7^\circ$. After matching, 29 of the 30 sources have median residuals below $10^\circ$. We also quantified how residual $Q/U$ offsets propagate in ratios of polarization fractions, differences in spectral indices, and polarization angles. These validations provide procedures and quantitative references for interpreting POL-2 measurements and combining them with polarimetry at other wavelengths.
Source: arXiv (Cornell University)
Authors: Furuya, Ray S., Berry, David, Bastien, Pierre, Hasegawa, Tetsuo, Matsumura, Masafumi, Kawabata, Koji, Iwasaki, Kazunari, Friberg, Per, Coudé, Simon, Fanciullo, Lapo, Hoang, Thiem, Doi, Yasuo, Li, Hua-bai, Wang, Jia-Wei, Ching, Tao-Chung, Shinnaga, Hiroko, Nakanishi, Hiroyuki, Graves, Sarah, Lyo, A-Ran, Liu, Junhao, Karoly, Janik, Hwang, Jihye, White, Glenn J., Arzoumanian, Doris, Sadavoy, Sarah, Tomisaka, Kohji, Diep, Pham Ngoc, Tahani, Mehrnoosh, Ngoc, Nguyen Bich, Soam, Archana, Yen, Hsi-Wei, Eswaraiah, Chakali, Könyves, Vera, Lee, Jeong-Eun, Gouellec, Valentin J. M. Le, Sharma, Ekta, Tram, Le Ngoc, Poidevin, Frédérick, Liu, Tie, Rawlings, Mark, Bijas, Najimudeen, Nakamura, Fumitaka, Friesen, Rachel, Robitaille, Jean-François, Misugi, Yoshiaki, Kashiwagi, Raiga, Onaka, Takashi, Tamura, Motohide, Parsons, Harriet, Bourke, Tyler L., Eden, David, Chen, Huei-Ru Vivien, Ohashi, Nagayoshi, Kim, Jongsoo, Lai, Shih-Ping, Qiu, Keping, Li, Di, Kwon, Woojin, Inutsuka, Shu-ichiro, Pattle, Kate, Ward-Thompson, Derek, Collaboration, BISTRO
Institutions: Tokushima University, East Asian Observatory, Centre for Research in Astrophysics of Québec, National Institutes of Natural Sciences, National Astronomical Observatory of Japan, Kagawa University, Tamkang University, Korea Astronomy and Space Science Institute, Korea University of Science and Technology, The University of Tokyo, Chinese University of Hong Kong, Institute of Astronomy and Astrophysics, Academia Sinica, Academia Sinica, Kagoshima University, University College London, Kyushu University, Kyushu University Institute for Advanced Study, The Open University, Queen's University, University of South Carolina, Indian Institute of Astrophysics, University of Lancashire, Seoul National University, Chinese Academy of Sciences, National Astronomical Observatories, Universidad de La Laguna, Instituto de Astrofísica de Canarias, Shanghai Astronomical Observatory, University of Manchester, The Graduate University for Advanced Studies, SOKENDAI, National Radio Astronomy Observatory, Centre National de la Recherche Scientifique, Institut de Planétologie et d'Astrophysique de Grenoble, SKA Observatory, Armagh Observatory & Planetarium, University of Bath, Institute of Astronomy, National Tsing Hua University, University of Chinese Academy of Sciences, Nanjing University, Université de Montréal
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Aeronautics and Space Administration, National Astronomical Research Institute of Thailand, Universities Space Research Association, Academia Sinica, Korea Astronomy and Space Science Institute, University of Tokushima, National Astronomical Observatory of Japan, Russian Science Foundation, Universität Stuttgart, Science and Technology Facilities Council, Japan Society for the Promotion of Science, National Institutes of Natural Sciences
Award: G5274026675
OpenAlex ID: W7223210539