A comparison between Galactic magnetic field models and polarized synchrotron emission with C-BASS at 4.76 GHz and S-PASS at 2.3 GHz

Fuente: arXiv
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Main Authors: Shaw, Vasundhara, Harper, S. E., Dickinson, C., Leahy, J. P., Hoerning, Gabriel A., Cepeda-Arroita, R., Weymann-Despres, Gilles, Peel, Mike, Taylor, Angela C., Pearson, T. J., Leech, Jamie, Jones, Michael
Format: Preprint
Published: 2026
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author Shaw, Vasundhara
Harper, S. E.
Dickinson, C.
Leahy, J. P.
Hoerning, Gabriel A.
Cepeda-Arroita, R.
Weymann-Despres, Gilles
Peel, Mike
Taylor, Angela C.
Pearson, T. J.
Leech, Jamie
Jones, Michael
author_facet Shaw, Vasundhara
Harper, S. E.
Dickinson, C.
Leahy, J. P.
Hoerning, Gabriel A.
Cepeda-Arroita, R.
Weymann-Despres, Gilles
Peel, Mike
Taylor, Angela C.
Pearson, T. J.
Leech, Jamie
Jones, Michael
contents We compare a set of contemporary Galactic magnetic field (GMF) models with polarized synchrotron observations from the S-PASS and C-BASS radio surveys and combine them to create a reconstructed 4.76~GHz full sky map. Pixels that potentially have a large Faraday rotation are excluded while small ($< 80\degree$) Faraday corrections derived at the respective frequencies of the two surveys are applied to the rest of the map. Using a template-fitting approach, we evaluate the ability of each model to reproduce the observed polarization amplitudes and polarization angles. We find that while most GMF models match the polarization angles reasonably well, they often fail to reproduce the morphology of the polarized intensity. We find that for most models there is a clear correlation between the data and models in polarization angles on large scales, but this does not hold true for polarized intensity. Our results show that a large portion of the polarized sky is shaped by local ``foreground'' features such as the North Polar Spur/Loop\,I and the Fan region. We conclude that incorporating such local structures is essential for accurately modelling the polarized synchrotron emission at microwave frequencies.
format Preprint
id arxiv_https___arxiv_org_abs_2605_23489
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A comparison between Galactic magnetic field models and polarized synchrotron emission with C-BASS at 4.76 GHz and S-PASS at 2.3 GHz
Shaw, Vasundhara
Harper, S. E.
Dickinson, C.
Leahy, J. P.
Hoerning, Gabriel A.
Cepeda-Arroita, R.
Weymann-Despres, Gilles
Peel, Mike
Taylor, Angela C.
Pearson, T. J.
Leech, Jamie
Jones, Michael
Astrophysics of Galaxies
High Energy Astrophysical Phenomena
We compare a set of contemporary Galactic magnetic field (GMF) models with polarized synchrotron observations from the S-PASS and C-BASS radio surveys and combine them to create a reconstructed 4.76~GHz full sky map. Pixels that potentially have a large Faraday rotation are excluded while small ($< 80\degree$) Faraday corrections derived at the respective frequencies of the two surveys are applied to the rest of the map. Using a template-fitting approach, we evaluate the ability of each model to reproduce the observed polarization amplitudes and polarization angles. We find that while most GMF models match the polarization angles reasonably well, they often fail to reproduce the morphology of the polarized intensity. We find that for most models there is a clear correlation between the data and models in polarization angles on large scales, but this does not hold true for polarized intensity. Our results show that a large portion of the polarized sky is shaped by local ``foreground'' features such as the North Polar Spur/Loop\,I and the Fan region. We conclude that incorporating such local structures is essential for accurately modelling the polarized synchrotron emission at microwave frequencies.
title A comparison between Galactic magnetic field models and polarized synchrotron emission with C-BASS at 4.76 GHz and S-PASS at 2.3 GHz
topic Astrophysics of Galaxies
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2605.23489