Full-sky Models of Galactic Microwave Emission and Polarization at Subarcminute Scales for the Python Sky Model
Creators
- The Pan-Experiment Galactic Science Group
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Borrill, Julian1, 2, 3
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Clark, Susan E.4
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Delabrouille, Jacques5, 1
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Frolov, Andrei V.6
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Ghosh, Shamik1, 5
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Hensley, Brandon S.7
- Hicks, Monica D.4
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Krachmalnicoff, Nicoletta8, 9, 10
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Lau, King11
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Norton, Myra M.12
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Pryke, Clement13
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Puglisi, Giuseppe14, 15, 16
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Remazeilles, Mathieu17
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Russier, Elisa5, 1
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Thorne, Benjamin1, 18
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Yao, Jian8
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Zonca, Andrea19
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1.
Lawrence Berkeley National Laboratory
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2.
University of California, Berkeley
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3.
University of Pennsylvania
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4.
Stanford University
- 5. CNRS-UCB International Research Laboratory, Centre Pierre Binétruy, IRL 2007, CPB-IN2P3, Berkeley, CA 94720, USA
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6.
Simon Fraser University
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7.
Jet Propulsion Lab
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8.
International School for Advanced Studies
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9.
Institute for Fundamental Physics of the Universe
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10.
INFN Sezione di Trieste
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11.
California Institute of Technology
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12.
Princeton University
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13.
University of Minnesota
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14.
University of Catania
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15.
INFN Sezione di Catania
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16.
Osservatorio Astrofisico di Catania
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17.
Institute of Physics of Cantabria
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18.
University of California, Davis
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19.
San Diego Supercomputer Center
Abstract
Polarized foreground emission from the Galaxy is one of the biggest challenges facing current and upcoming cosmic microwave background (CMB) polarization experiments. We develop new models of polarized Galactic dust and synchrotron emission at CMB frequencies that draw on the latest observational constraints; that employ the "polarization fraction tensor" framework to couple intensity and polarization in a physically motivated way; and that allow for stochastic realizations of small-scale structure at subarcminute angular scales currently unconstrained by full-sky data. We implement these models into the publicly available Python Sky Model (PySM) software and additionally provide PySM interfaces to select models of dust and CO emission from the literature. We characterize the behavior of each model by quantitatively comparing it to observational constraints in both maps and power spectra, demonstrating an overall improvement over previous PySM models. Finally, we synthesize models of the various Galactic foreground components into a coherent suite of three plausible microwave skies that span a range of astrophysical complexity allowed by current data. Author contributions to this paper can be found at the end of this work.
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
We thank the Atacama Cosmology Telescope (ACT), BICEP/Keck, BLAST, CCAT, CMB-S4, LiteBIRD, Simons Observatory (SO), and South Pole Telescope (SPT) Collaborations for their support of the Pan-Experiment Galactic Science Group, which coordinated this community-wide effort. We thank the BICEP/Keck Collaboration for sharing the BK18 matrix products used in this study. We are grateful to Irene Abril-Cabezas, Carlo Baccigalupi, Colin Bischoff, Dick Bond, François Boulanger, Yi-Kuan Chiang, Tuhin Ghosh, Bill Jones, François Levrier, Fazlu Rahman, and many other members of the Pan-Experiment Galactic Science Group for stimulating discussions that motivated and improved this work. We thank the anonymous referee for helpful feedback.
Funding
This work was supported by the National Science Foundation under grant Nos. AST-2106607 and AST-2441452 (PI: S.E.C.). S.E.C. additionally acknowledges support from an Alfred P. Sloan Research Fellowship. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 using NERSC award HEP-ERCAP0032657. N.K. and M.R. acknowledge support by the RadioForegroundsPlus Project HORIZON-CL4-2023-SPACE-01, GA 101135036. M.M.N. acknowledges support from the Princeton Undergraduate Summer Research Program. M.D.H. and S.E.C. acknowledge support from the Stanford Physics Undergraduate Summer Research Program. M.R. acknowledges the support of the Spanish Ministry of Science and Innovation through grant Nos. PID2022-139223OB-C21 and PID2022-140670NA-I00. This work was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
Additional Information
Some of the results in this paper have been derived using the healpy and HEALPix packages.
Software References
Astropy (Astropy Collaboration et al. 2013, 2018, 2022); cmocean (K. M. Thyng et al. 2016); HEALPix (K. M. Górski et al. 2005); healpy (A. Zonca et al. 2019); Matplotlib (J. D. Hunter 2007); NaMaster (D. Alonso et al. 2019); NumPy (S. van der Walt et al. 2011; C. R. Harris et al. 2020); Pynkowski (https://javicarron.github.io/pynkowski/pynkowski.html); PySM (B. Thorne et al. 2017; A. Zonca et al. 2021); SciPy (P. Virtanen et al. 2020).
Files
Borrill_2025_ApJ_991_23.pdf
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Additional details
Related works
- Is new version of
- Discussion Paper: arXiv:2502.20452 (arXiv)
Funding
- National Science Foundation
- AST-2106607
- National Science Foundation
- AST-2441452
- Alfred P. Sloan Foundation
- United States Department of Energy
- DE-AC02-05CH11231
- National Energy Research Scientific Computing Center
- HEP-ERCAP0032657
- European Union
- HORIZON-CL4-2023-SPACE-0 GA 101135036
- Princeton University
- Stanford University
- Ministerio de Ciencia, Innovación y Universidades
- PID2022-139223OB-C21
- Ministerio de Ciencia, Innovación y Universidades
- PID2022-140670NA-I00
Dates
- Accepted
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2025-07-18
- Available
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2025-09-12Published