Analysis of Polarized Dust Emission Using Data from the First Flight of SPIDER

Creators: Ade, P. A. R.¹; Amiri, M.²; Benton, S. J.³; Bergman, A. S.³; Bihary, R.⁴; Bock, J. J.^{5, 6}; Bond, J. R.⁷; Bonetti, J. A.⁶; Bryan, S. A.⁸; Chiang, H. C.^{9, 10}; Contaldi, C. R.¹¹; Doré, O.⁵; Duivenvoorden, A. J.^{3, 12}; Eriksen, H. K.¹³; Filippini, J. P.¹⁴; Fraisse, A. A.³; Freese, K.¹⁵; Galloway, M.¹³; Gambrel, A. E.¹⁶; Gandilo, N. N.¹⁷; Ganga, K.¹⁸; Gourapura, S.³; Gualtieri, R.^{14, 19}; Gudmundsson, J. E.^{20, 21}; Halpern, M.²; Hartley, J.²²; Hasselfield, M.²³; Hilton, G.²⁴; Holmes, W.⁶; Hristov, V. V.⁵; Huang, Z.⁷; Irwin, K. D.^{25, 26}; Jones, W. C.³; Karakci, A.¹³; Kuo, C. L.²⁵; Kermish, Z. D.³; Leung, J. S.-Y.²²; Li, S.³; Mak, D. S. Y.¹¹; Mason, P. V.⁵; Megerian, K.⁶; Moncelsi, L.⁵; Morford, T. A.⁵; Nagy, J. M.⁴; Netterfield, C. B.²²; Nolta, M.⁷; O'Brient, R.⁶; Osherson, B.¹⁴; Padilla, I. L.^{4, 22, 27}; Racine, B.¹³; Rahlin, A. S.¹⁶; Reintsema, C.²⁴; Ruhl, J. E.⁴; Runyan, M. C.⁵; Ruud, T. M.¹³; Shariff, J. A.⁷; Shaw, E. C.^{14, 28, 29}; Shiu, C.³; Soler, J. D.³⁰; Song, X.³; Trangsrud, A.^{5, 6}; Tucker, C.¹; Tucker, R. S.⁵; Turner, A. D.⁶; van der List, J. F.³; Weber, A. C.⁶; Wehus, I. K.¹³; Wiebe, D. V.²; Young, E. Y.^{25, 26}; Spider Collaboration

1. Cardiff University
2. University of British Columbia
3. Princeton University
4. Case Western Reserve University
5. California Institute of Technology
6. Jet Propulsion Lab
7. Canadian Institute for Theoretical Astrophysics
8. Arizona State University
9. McGill University
10. University of KwaZulu-Natal
11. Imperial College London
12. Center for Computational Astrophysics, Flatiron Institute, New York, NY 10010, USA
13. University of Oslo
14. University of Illinois Urbana-Champaign
15. University of Texas
16. University of Chicago
17. University of Arizona
18. Astroparticle and Cosmology Laboratory
19. Northwestern University
20. Stockholm University
21. University of Iceland
22. University of Toronto
23. Pennsylvania State University
24. National Institute of Standards and Technology
25. Stanford University
26. SLAC National Accelerator Laboratory
27. Johns Hopkins University
28. Department of Physics, University of Texas, 2515 Speedway, C1600, Austin, TX 78712, USA
29. Weinberg Institute for Theoretical Physics, Texas Center for Cosmology and Astroparticle Physics, Austin, TX 78712, USA
30. Max Planck Institute for Astronomy

Abstract

Using data from the first flight of Spider and from the Planck High Frequency Instrument, we probe the properties of polarized emission from interstellar dust in the Spider observing region. Component-separation algorithms operating in both the spatial and harmonic domains are applied to probe their consistency and to quantify modeling errors associated with their assumptions. Analyses of diffuse Galactic dust emission spanning the full Spider region demonstrate (i) a spectral energy distribution that is broadly consistent with a modified-blackbody (MBB) model with a spectral index of β_d = 1.45 ± 0.05 (1.47 ± 0.06) for E (B)-mode polarization, slightly lower than that reported by Planck for the full sky; (ii) an angular power spectrum broadly consistent with a power law; and (iii) no significant detection of line-of-sight polarization decorrelation. Tests of several modeling uncertainties find only a modest impact (∼10% in σ_r) on Spider's sensitivity to the cosmological tensor-to-scalar ratio. The size of the Spider region further allows for a statistically meaningful analysis of the variation in foreground properties within it. Assuming a fixed dust temperature T_d = 19.6 K, an analysis of two independent subregions of that field results in inferred values of β_d = 1.52 ± 0.06 and β_d = 1.09 ± 0.09, which are inconsistent at the 3.9σ level. Furthermore, a joint analysis of Spider and Planck 217 and 353 GHz data within one subregion is inconsistent with a simple MBB at more than 3σ, assuming a common morphology of polarized dust emission over the full range of frequencies. This evidence of variation may inform the component-separation approaches of future cosmic microwave background polarization experiments.

Copyright and License

© 2025. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Acknowledgement

Spider is supported in the U.S. by the National Aeronautics and Space Administration under grants NNX07AL64G, NNX12AE95G, NNX17AC55G, and 80NSSC21K1986 issued through the Science Mission Directorate, and by the National Science Foundation through PLR-1043515. Logistical support for the Antarctic deployment and operations was provided by the NSF through the U.S. Antarctic Program. Support in Canada is provided by the Natural Sciences and Engineering Research Council and the Canadian Space Agency. Support in Norway is provided by the Research Council of Norway. The Dunlap Institute is funded through an endowment established by the David Dunlap family and the University of Toronto. The Flatiron Institute is supported by the Simons Foundation. J.E.G. acknowledges support from the Swedish Research Council (Reg. No. 2019-03959) and the Swedish National Space Agency (SNSA/Rymdstyrelsen). This work is in part funded by the European Union (ERC, CMBeam, 101040169). J.M.N. acknowledges support from the Research Corporation for Science Advancement. K.F. acknowledges support from DOE grant DE-SC0007859 at the University of Michigan. We also wish to acknowledge the generous support of the David and Lucile Packard Foundation, which has been crucial to the success of the project.

The collaboration is grateful to the British Antarctic Survey, particularly Sam Burrell, for invaluable assistance with data and payload recovery after the 2015 flight. We thank Brendan Crill and Tom Montroy for significant contributions to Spider's development. Some of the results in this paper have been derived using the HEALPix package (K. M. Gorski et al. 2005). The computations described in this paper were performed on the GPC supercomputer at the SciNet HPC Consortium (C. Loken et al. 2010). SciNet is funded by the Canada Foundation for Innovation under the auspices of Compute Canada, the Government of Ontario, Ontario Research Fund—Research Excellence, and the University of Toronto.

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