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  • Open Access

Axion-photon conversion in stochastic magnetic fields

Wataru Chiba1,*, Ryusuke Jinno1,†, and Kimihiro Nomura2,‡

  • 1Department of Physics, Graduate School of Science, Kobe University, 1-1 Rokkodai, Kobe, Hyogo 657-8501, Japan
  • 2Department of Physics, Kyoto University, Kyoto 606-8502, Japan

  • *Contact author: 245s114s@stu.kobe-u.ac.jp
  • †Contact author: jinno@phys.sci.kobe-u.ac.jp
  • ‡Contact author: k.nomura@tap.scphys.kyoto-u.ac.jp
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Phys. Rev. D 113, 115037 – Published 15 June, 2026

DOI: https://doi.org/10.1103/5gkl-hk9d

Abstract

We investigate axion-photon conversion in stochastic magnetic fields, focusing on the evolution of the photon intensity and polarizations induced by conversion into axions. Assuming Gaussian magnetic fields characterized by the power spectra of their helical/nonhelical components, we express the expectation values and variances of the photon intensity and linear/circular polarizations after conversion in terms of these spectra. We find nontrivial dependencies of these statistical quantities on the characteristic magnetic-field correlation length, the propagation distance, and the axion mass. Moreover, we find that nontrivial polarizations emerge even if the photons are initially unpolarized, that the variances of these observables become suppressed in specific frequency regions, and that a peak structure arises in the expectation value of the circular polarization in the presence of statistically helical magnetic fields. We also point out consistency relations among these statistical quantities that hold independently of the specific forms of the magnetic-field power spectra.

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Outline

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Phys. Rev. D 113, 115037– Published 15 June, 2026
  • Received 24 December 2025
  • Accepted 19 May 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

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