Published January 15, 2026 | Version Supplemental material
Journal Article Open

A sudden change and recovery in the magnetic environment around a repeating fast radio burst

  • 1. ROR icon Purple Mountain Observatory
  • 2. ROR icon University of Science and Technology of China
  • 3. ROR icon Australia Telescope National Facility
  • 4. ROR icon Yunnan University
  • 5. ROR icon National Astronomical Observatories
  • 6. ROR icon Beijing Normal University
  • 7. ROR icon California Institute of Technology
  • 8. ROR icon West Virginia University
  • 9. ROR icon Netherlands Institute for Radio Astronomy
  • 10. ROR icon University of Amsterdam
  • 11. ROR icon Peking University
  • 12. ROR icon Shanghai Astronomical Observatory
  • 13. ROR icon Zhejiang Lab
  • 14. ROR icon Zhejiang University
  • 15. ROR icon Princeton University
  • 16. ROR icon Tsinghua University
  • 17. ROR icon McGill University
  • 18. ROR icon Massachusetts Institute of Technology
  • 19. ROR icon National Time Service Center
  • 20. ROR icon University of Pennsylvania
  • 21. ROR icon Carnegie Mellon University
  • 22. ROR icon Guangzhou University
  • 23. ROR icon Anhui University of Science and Technology
  • 24. ROR icon Guizhou University
  • 25. ROR icon University of Hong Kong
  • 26. Nevada Center for Astrophysics, University of Nevada, Las Vegas, NV, USA.
  • 27. Department of Physics and Astronomy, University of Nevada, Las Vegas, NV, USA.

Abstract

Fast radio bursts (FRBs) are millisecond-duration radio transients from extragalactic sources. Some repeating FRBs exhibit variations in their Faraday rotation measure (RM) due to changes in their magneto-ionic environment. We report magneto-ionic variations of FRB 20220529, a repeating FRB from a disk galaxy at redshift 0.18. For the first 17 months of observations, the RM had a median of 17 radians per square meter (rad m−2) and a scatter of 101 rad m−2. In December 2023, the RM jumped to 1977 ± 84 rad m−2, then gradually returned to typical values within 2 weeks. This sudden RM variation indicates that a dense magnetized clump of plasma passed across the line of sight. We discuss potential explanations, including a coronal mass ejection from a companion star, high plasma turbulence, or binary orbital motion.

Copyright and License

© 2026 the authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original US government works. https://www.science.org/about/science-licenses-journal-article-reuse

Acknowledgement

We thank three anonymous referees for their helpful suggestions. We also thank Q. Yuan, J. Hu, L. Lu, J. Yang, X.-T. Fu, M. Fang, J. Yu, H.-P. Lu, B.-Y. Liu, and J. Li for helpful discussions. This work made use of data from FAST, a Chinese national megascience facility, built and operated by the National Astronomical Observatories, Chinese Academy of Sciences. The Parkes radio telescope (Murriyang) is part of the Australia Telescope National Facility, which is funded by the Australian government for operation as a National Facility managed by the Commonwealth Scientific and Industrial Research Organisation (CSIRO). This study also used data collected at Karl G. Jansky Very Large Array, operated by the National Radio Astronomy Observatory (NRAO). The NRAO is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We acknowledge the use of public data from the DESI Legacy Survey. We acknowledge the support and assistance provided by the staff of the Gran Telescopio Canarias (GTC). This research has made use of the CHIME/FRB VOEvent Service.

Funding

The authors were supported by National Natural Science Foundation of China (NSFC) grants 12321003 (X.F.W.), 12041306 (Y.L., S.B.Z., X.F.W., J.J.G.), 12393813 (Y.L., X.F.W., J.J.G., D.X.), 12503058 (S.B.Z.), 12473047 (Y.P.Y.), 12041303 (W.W.Z.), 12421003 (W.W.Z., P.J.), 12225303 (P.J.), 12203045 (Y.F.), 12503055 (J.R.N.), 12273113 (J.J.G.), 11988101 (J.L.H.), 11833009 (J.L.H.), 12588202 (J.L.H.), 12303042 (R.L.), and 12303015 (D.D.S.); National SKA Program of China grants 2022SKA0130100 (Y.L., S.B.Z., X.F.W.), 2022SKA0130101, 2020SKA0120200 (W.W.Z.), and 2022SKA0120103 (J.L.H.); International Partnership Program of Chinese Academy of Sciences for Grand Challenges grant 114332KYSB20210018 (Y.L., S.B.Z., X.Y., J.J.G., X.F.W.); CAS Project for Young Scientists in Basic Research grant YSBR-063 (W.W.Z., P.J., J.J.G.); the CAS Organizational Scientific Research Platform for National Major Scientific and Technological Infrastructure: Cosmic Transients with FAST (X.F.W.); Strategic Priority Research Program of the Chinese Academy of Sciences grants XDB0550400 (Y.L.) and XDA0350501 (P.J.); and Postdoctoral Fellowship Program of CPSF grants GZC20252100 (X.Y.) and GZB20250737 (J.R.N). Y.L. is supported by National Key R&D Program of China grant 2024YFA1611704. S.B.Z. is an ACAMAR Postdoctoral Fellow. Y.P.Y. is supported by National Key Research and Development Program of China grant 2024YFA1611603, Yunnan Key Laboratory of Survey Science grant 202449CE340002, and two Team Projects—Innovation Team grant 202105AE160021 and Top Team grant 202305AT350002—funded by the Yunnan Revitalization Talent Support Program. W.W.Z. is supported by Beijing Nova Program grant 20250484786 and the CAS-MPG LEGACY project. P.J. is supported by the New Cornerstone Science Foundation through the Xplorer Prize, and Guizhou Province High-level Talent Program grant QKHPTRC-GCC[2022]003-2. X.Y. is supported by China Postdoctoral Science Foundation grant 2025M773201 and the Jiangsu Funding Program for Excellent Postdoctoral Talent. J.J.G. is supported by Youth Innovation Promotion Association grant 2023331. D.L. is supported by the New Cornerstone Investigator Program. D.D.S. is supported by Natural Science Foundation of Jiangsu Province grant BK20231106.

Data Availability

The reduced FAST observations of the bursts with RM measurements during the RM flare are archived at Zenodo (49). The Parkes data are available at https://data.csiro.au/domain/atnf under projects P1105 and P1183 and the source name FRB20220529. The VLA data are available at https://data.nrao.edu/portal/ under project code 23A-385. The GTC data are available at https://gtc.sdc.cab.inta-csic.es/gtc/jsp/searchform.jsp under program ID GTCMULTIPLE1A-23ACNT. The reduced GTC spectrum is available at https://github.com/Astroyx/FRB20220529 and archived at Zenodo (49). Our measured and derived properties for all observed bursts are listed in Table 2 and tables S4 to S6. A machine-readable version of table S5 is archived at Zenodo (49). Our best-fitting model parameters are provided in table S3. No physical materials were generated in this work.

Supplemental Material

Materials and Methods
Supplementary Text
Figs. S1 to S11
Tables S1 to S6
References (50–124)

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Identifiers

Related works

Describes
Journal Article: 41538449 (PMID)

Funding

National Natural Science Foundation of China
12321003
National Natural Science Foundation of China
12041306
National Natural Science Foundation of China
12393813
National Natural Science Foundation of China
12503058
National Natural Science Foundation of China
12473047
National Natural Science Foundation of China
12041303
National Natural Science Foundation of China
12421003
National Natural Science Foundation of China
12225303
National Natural Science Foundation of China
12203045
National Natural Science Foundation of China
12503055
National Natural Science Foundation of China
12273113
National Natural Science Foundation of China
11988101
National Natural Science Foundation of China
11833009
National Natural Science Foundation of China
12588202
National Natural Science Foundation of China
12303042
National Natural Science Foundation of China
12303015
the National SKA Program of China
2022SKA0130100
the National SKA Program of China
2022SKA0130101
the National SKA Program of China
2020SKA0120200
the National SKA Program of China
2022SKA0120103
International Partnership Program of Chinese Academy of Sciences for Grand Challenges
114332KYSB20210018
the CAS Project for Young Scientists in Basic Research
YSBR-063
CAS Organizational Scientific Research Platform for National Major Scientific and Technological Infrastructure
Cosmic Transients with FAST
Strategic the Priority Research Program of the Chinese Academy of Sciences
XDB0550400
the Priority Research Program of the Chinese Academy of Sciences
XDA0350501
Postdoctoral Fellowship Program of CPSF
GZC20252100
Postdoctoral Fellowship Program of CPSF
GZB20250737
National key R&D program of China
2024YFA1611704
the ACAMAR Postdoctoral Fellow
The National Key Research and Development Program of China
2024YFA1611603
the Yunnan Key Laboratory of Survey Science
202449CE340002
the Yunnan Revitalization Talent Support Program
202105AE160021
the Yunnan Revitalization Talent Support Program
202305AT350002
Beijing Municipal Science and Technology Commission
20250484786
CAS-MPG LEGACY project
The New Cornerstone Science Foundation
Xplorer Prize
Guizhou Province High-level Talent Program
QKHPTRC-GCC[2022]003-2
China Postdoctoral Science Foundation
2025M773201
Jiangsu Funding Program for Excellent Postdoctoral Talent
the Youth Innovation Promotion Association
2023331
The New Cornerstone Investigator Program
new Cornerstone investigator
the Natural Science Foundation of Jiangsu Province
BK20231106

Dates

Submitted
2024-05-16
Accepted
2025-11-18

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