NuSTAR as an Axion Helioscope
Creators
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1.
TU Dortmund University
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2.
University of Zaragoza
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3.
University of Nottingham
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4.
University of Turin
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5.
INFN Sezione di Torino
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6.
Barry University
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7.
California Institute of Technology
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8.
University of Glasgow
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9.
University of California, Santa Barbara
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10.
Instituto de Astrofísica de Canarias
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11.
Spanish National Research Council
Abstract
We present a novel approach to investigating axions and axionlike particles by studying their potential conversion into x-rays within the Sun's atmospheric magnetic field. Utilizing high-sensitivity data from the nuclear spectroscopic telescope array (NuSTAR) collected during the 2020 solar minimum, along with advanced solar atmospheric magnetic field models, we establish a new limit on the axion-photon coupling strength gaγ ≲ 7.3×10⁻¹² GeV⁻¹ at 95% CL for axion masses ma ≲ 4×10⁻⁷ eV. This constraint surpasses current ground-based experimental limits, studying previously unexplored regions of the axion-photon coupling parameter space up to masses of ma ≲ 3.4×10⁻⁴ eV. These findings mark a significant advancement in our ability to probe axion properties and strengthen indirect searches for dark matter candidates.
Copyright and License
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.
Acknowledgement
We gratefully acknowledge the support of the NuSTAR operations, software, and calibration teams in the execution and analysis of these observations. Our thanks also extend to Georg G. Raffelt, Jiří Štěpan, and T. O’Shea for insightful discussions. E. T., M. R., and M. T. are supported by the project “Theoretical Astroparticle Physics (TAsP)” funded by INFN and the “Grant for Internationalization” from the University of Torino. M. T. further acknowledges the research grant “Addressing Systematic Uncertainties in Searches for Dark Matter No. 2022F2843L” funded by MIUR. E. T. expresses gratitude to the University of Zaragoza for its hospitality during the initial phases of this work. This publication is based on work supported by COST Action COSMIC WISPers CA21106.
Data Availability
The data that support the findings of this article are openly available [114].
Supplemental Material
The supplemental material provides a detailed account of the solar axion flux and its variation with solar radius, a comprehensive modeling of the coronal magnetic field, and an explanation of the anticipated X-ray signal detectable by the NuSTAR satellite. It also includes information on data selection criteria and the specifics of the NuSTAR analysis. Additionally, we examine the systematic uncertainties influencing the newly derived axion limit and evaluate the significance of the NuSTAR results in the context of prior laboratory experiments and astrophysical constraints.
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18sn-hxtb.pdf
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Additional details
Related works
- Is new version of
- Discussion Paper: arXiv:2407.03828 (arXiv)
- Is supplemented by
- Supplemental Material: https://journals.aps.org/prl/supplemental/10.1103/18sn-hxtb/supplemental_material_refs_as_in_main.pdf (URL)
- Dataset: https://github.com/elisabm99/nustar-helioscope (URL)
Funding
- Istituto Nazionale di Fisica Nucleare
- University of Turin
- Ministero dell'Istruzione, dell'Università e della Ricerca
- 2022F2843L
- European Cooperation in Science and Technology
- CA21106
Dates
- Accepted
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2025-08-19