B-fields In STar-forming Region Observations (BISTRO): Technical Foundations for Quantitative 450/850 μm JCMT SCUBA-2/POL-2 Polarimetry
Abstract
We present five technical validations of SCUBA-2/POL-2 polarimetry on the James Clerk Maxwell Telescope at 450 and 850 μm, 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 μm 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 μm 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 μm support the correction in strongly affected fields. We matched the 450 μm maps to the modeled 850 μm beam and the common 12.6''-300'' range of angular scales. We compared three reductions of the same 450 μm 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∘ to 4.7∘. After matching, 29 of the 30 sources have median residuals below 10∘. 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.
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BibTeX
@misc{furuya2026bfields,
title = {{B-fields In STar-forming Region Observations (BISTRO): Technical Foundations for Quantitative 450/850 $μ$m JCMT SCUBA-2/POL-2 Polarimetry}},
author = {Ray S. Furuya and David Berry and Pierre Bastien and Tetsuo Hasegawa and Masafumi Matsumura and Koji Kawabata and Kazunari Iwasaki and Per Friberg and Simon Coudé and Lapo Fanciullo and Thiem Hoang and Yasuo Doi and Hua-bai Li and Jia-Wei Wang and Tao-Chung Ching and Hiroko Shinnaga and Hiroyuki Nakanishi and Sarah Graves and A-Ran Lyo and Junhao Liu and Janik Karoly and Jihye Hwang and Glenn J. White and Doris Arzoumanian and Sarah Sadavoy and Kohji Tomisaka and Pham Ngoc Diep and Mehrnoosh Tahani and Nguyen Bich Ngoc and Archana Soam and Hsi-Wei Yen and Chakali Eswaraiah and Vera Könyves and Jeong-Eun Lee and Valentin J. M. Le Gouellec and Ekta Sharma and Le Ngoc Tram and Frédérick Poidevin and Tie Liu and Mark Rawlings and Najimudeen Bijas and Fumitaka Nakamura and Rachel Friesen and Jean-François Robitaille and Yoshiaki Misugi and Raiga Kashiwagi and Takashi Onaka and Motohide Tamura and Harriet Parsons and Tyler L. Bourke and David Eden and Huei-Ru Vivien Chen and Nagayoshi Ohashi and Jongsoo Kim and Shih-Ping Lai and Keping Qiu and Di Li and Woojin Kwon and Shu-ichiro Inutsuka and Kate Pattle},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.29273},
eprint = {2610.29273},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.29273},
}
RIS
TY - UNPB
TI - B-fields In STar-forming Region Observations (BISTRO): Technical Foundations for Quantitative 450/850 μm JCMT SCUBA-2/POL-2 Polarimetry
AU - Ray S. Furuya
AU - David Berry
AU - Pierre Bastien
AU - Tetsuo Hasegawa
AU - Masafumi Matsumura
AU - Koji Kawabata
AU - Kazunari Iwasaki
AU - Per Friberg
AU - Simon Coudé
AU - Lapo Fanciullo
AU - Thiem Hoang
AU - Yasuo Doi
AU - Hua-bai Li
AU - Jia-Wei Wang
AU - Tao-Chung Ching
AU - Hiroko Shinnaga
AU - Hiroyuki Nakanishi
AU - Sarah Graves
AU - A-Ran Lyo
AU - Junhao Liu
AU - Janik Karoly
AU - Jihye Hwang
AU - Glenn J. White
AU - Doris Arzoumanian
AU - Sarah Sadavoy
AU - Kohji Tomisaka
AU - Pham Ngoc Diep
AU - Mehrnoosh Tahani
AU - Nguyen Bich Ngoc
AU - Archana Soam
AU - Hsi-Wei Yen
AU - Chakali Eswaraiah
AU - Vera Könyves
AU - Jeong-Eun Lee
AU - Valentin J. M. Le Gouellec
AU - Ekta Sharma
AU - Le Ngoc Tram
AU - Frédérick Poidevin
AU - Tie Liu
AU - Mark Rawlings
AU - Najimudeen Bijas
AU - Fumitaka Nakamura
AU - Rachel Friesen
AU - Jean-François Robitaille
AU - Yoshiaki Misugi
AU - Raiga Kashiwagi
AU - Takashi Onaka
AU - Motohide Tamura
AU - Harriet Parsons
AU - Tyler L. Bourke
AU - David Eden
AU - Huei-Ru Vivien Chen
AU - Nagayoshi Ohashi
AU - Jongsoo Kim
AU - Shih-Ping Lai
AU - Keping Qiu
AU - Di Li
AU - Woojin Kwon
AU - Shu-ichiro Inutsuka
AU - Kate Pattle
PY - 2026
DA - 2026/10/21
PB - arXiv
DO - 10.48550/arxiv.2610.29273
UR - https://arxiv.org/abs/2610.29273
AB - We present five technical validations of SCUBA-2/POL-2 polarimetry on the James Clerk Maxwell Telescope at 450 and 850 μm, 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 μm 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 μm 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 μm support the correction in strongly affected fields. We matched the 450 μm maps to the modeled 850 μm beam and the common 12.6''-300'' range of angular scales. We compared three reductions of the same 450 μm 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^∘ to 4.7^∘. After matching, 29 of the 30 sources have median residuals below 10^∘. 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.
ER -