Abstract
Recently, a class of long-period radio transients (LPTs) has been discovered, exhibiting emission thousands of times longer than radio pulsars1,2,3,4,5. These findings, enabled by advances in wide-field radio surveys, challenge existing models of rotationally powered pulsars. Proposed models include highly magnetized neutron stars6, white-dwarf pulsars7 and white-dwarf binary systems with low-mass companions8. Although some models predict X-ray emission6,9, no LPTs have been detected in X-rays despite extensive searches1,2,3,4,5,10. Here we report the discovery of an extremely bright LPT (10–20 Jy in radio), ASKAP J1832−0911, which has coincident radio and X-ray emission, both with a 44.2-minute period. Its correlated and highly variable X-ray and radio luminosities, combined with other observational properties, are unlike any known Galactic object. The source could be an old magnetar or an ultra-magnetized white dwarf; however, both interpretations present theoretical challenges. This X-ray detection from an LPT reveals that these objects are more energetic than previously thought and establishes a class of hour-scale periodic X-ray transients with a luminosity of about 1033 erg s−1 linked to exceptionally bright coherent radio emission.
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Data availability
The data that support the findings of this study are available on Zenodo at https://doi.org/10.5281/zenodo.15228816 (ref. 76) and GitHub at https://github.com/Andywang201605/J1832-0911_radio_xray. All the ASKAP data are publicly available via CASDA (https://data.csiro.au/domain/casdaObservation). The MeerKAT data used in this study are available via the SARAO archive (https://archive.sarao.ac.za) under project ID DDT-20240213-AW-01. The ATCA data used in this study are available via the Australia Telescope Online Archive (https://atoa.atnf.csiro.au/) under project ID C3363. Other specific data are available on request from the corresponding author.
Code availability
The code that supports the findings of this study is available on GitHub at https://github.com/Andywang201605/J1832-0911_radio_xray. Specific scripts used in the data analysis are available on request from the corresponding author.
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Acknowledgements
We thank B. Gaensler, S. Dai and F. Coti Zelati for valuable discussions. We are grateful to the ASKAP engineering and operations team for their assistance in developing fast radio burst instrumentation for the telescope and supporting the survey. This work uses data obtained from Inyarrimanha Ilgari Bundara/the CSIRO Murchison Radio-astronomy Observatory. We acknowledge the Wajarri Yamaji People as the Traditional Owners and native title holders of the observatory site. CSIRO’s ASKAP radio telescope is part of the Australia Telescope National Facility (https://ror.org/05qajvd42). Operation of ASKAP is funded by the Australian Government with support from the National Collaborative Research Infrastructure Strategy. ASKAP uses the resources of the Pawsey Supercomputing Research Centre. Establishment of ASKAP, Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio-astronomy Observatory and the Pawsey Supercomputing Research Centre are initiatives of the Australian Government, with support from the Government of Western Australia and the Science and Industry Endowment Fund. CRACO was funded through Australian Research Council Linkage Infrastructure Equipment, and Facilities grant LE210100107. We thank the staff of the GMRT that made these observations possible. GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. We thank SARAO for the approval of the MeerKAT DDT request DDT-20240213-AW-01.The MeerKAT telescope is operated by the South African Radio Astronomy Observatory, which is a facility of the National Research Foundation, an agency of the Department of Science and Innovation. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We thank M. Bailes for supporting the PTUSE backend machine used in the MeerKAT observation. PTUSE was developed with support from the Australian SKA Office and Swinburne University of Technology. This research has made use of data obtained from the Chandra Data Archive provided by the Chandra X-ray Center (CXC). We acknowledge the use of public data from the Swift data archive. This research is based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. We thank the Einstein Probe principal investigator (W. Yuan) for accepting our ToO observation, Y. Chen as the FXT principal investigator, and the Einstein Probe Science Center for performing the observations. Einstein Probe is a space mission supported by the Strategic Priority Program of the Space Science of the Chinese Academy of Sciences (grant number XDB0550200), in collaboration with ESA, MPE and CNES (grant number XDA15310000), and the National Key R&D Program of China (2022YFF0711500). This paper includes data gathered with the 6.5-meter Magellan Telescope located at Las Campanas Observatory, Chile. Part of this work was performed on the OzSTAR national facility at Swinburne University of Technology. The OzSTAR programme receives funding in part from the Astronomy National Collaborative Research Infrastructure Strategy (NCRIS) allocation provided by the Australian Government, and from the Victorian Higher Education State Investment Fund (VHESIF) provided by the Victorian Government. We acknowledge the use of the ilifu cloud computing facility (www.ilifu.ac.za), a partnership between the University of Cape Town, the University of the Western Cape, Stellenbosch University, Sol Plaatje University, the Cape Peninsula University of Technology and the South African Radio Astronomy Observatory. The ilifu facility is supported by contributions from the Inter-University Institute for Data Intensive Astronomy (IDIA, a partnership between the University of Cape Town, the University of Pretoria and the University of the Western Cape), the Computational Biology division at UCT and the Data Intensive Research Initiative of South Africa (DIRISA). This work was carried out using the data-processing pipelines developed at the Inter-University Institute for Data Intensive Astronomy (IDIA) and available at https://idia-pipelines.github.io. IDIA is a partnership of the University of Cape Town, the University of Pretoria and the University of the Western Cape. This work made use of the CARTA (Cube Analysis and Rendering Tool for Astronomy) software (https://doi.org/10.5281/zenodo.3377984 and https://cartavis.github.io). This research has made use of the NASA Astrophysics Data System. N.R. is supported by the European Research Council (ERC) via the Consolidator Grant ‘MAGNESIA’ (number 817661) and the Proof of Concept ‘DeepSpacePulse’ (number 101189496), by the Catalan grant SGR2021-01269 (principal investigator V. Graber/N.R.), the Spanish grant ID2023-153099NA-I00 (principal investigator F. Coti Zelati), and by the programme Unidad de Excelencia Maria de Maeztu CEX2020-001058-M. T.B. acknowledges financial support from the Framework per l’Attrazione e il Rafforzamento delle Eccellenze (FARE) per la ricerca in Italia (R20L5S39T9). D.L.K. is supported by NSF grant AST-1816492. The material is based upon work supported by NASA under award number 80GSFC24M0006. Z. Wadiasingh, J.H. and G.Y. acknowledge support by NASA under award numbers 80GSFC21M0002 and 80GSFC21M0006. P.B. acknowledges support from a NASA grant 80NSSC24K0770, a grant (number 2020747) from the United States-Israel Binational Science Foundation (BSF), Jerusalem, Israel and by a grant (number 1649/23) from the Israel Science Foundation. A.J.C. acknowledges support from the Oxford Hintze Centre for Astrophysical Surveys, which is funded through generous support from the Hintze Family Charitable Foundation. Basic research in radio astronomy at the US Naval Research Laboratory is supported by 6.1 Base funding. Construction and installation of VLITE was supported by the NRL Sustainment Restoration and Maintenance fund. M.G. is supported by the Australian Government through the Australian Research Council’s Discovery Projects funding scheme (DP210102103), and through UK STFC Grant ST/Y001117/1. M.G. acknowledges support from the Inter-University Institute for Data Intensive Astronomy (IDIA). IDIA is a partnership of the University of Cape Town, the University of Pretoria and the University of the Western Cape. For the purpose of open access, the author has applied a Creative Commons Attribution (CC BY) licence to any author accepted manuscript version arising from this submission. N.H.-W. is the recipient of an Australian Research Council Future Fellowship (project number FT190100231) funded by the Australian Government. M.C. acknowledges the support of an Australian Research Council Discovery Early Career Research Award (project number DE220100819) funded by the Australian Government. C.W.J. acknowledges support by the Australian Government through the Australian Research Council’s Discovery Projects funding scheme (project DP210102103). M.E.L. receives support from the ARC Discovery Early Career Research Award DE250100508. The Chandra X-ray observation presented in this paper and partial funding for K.M. are supported by SAO grant GO3-24121X. M.P.-T. acknowledges financial support from the Severo Ochoa grant CEX2021-001131-S and from the National grant PID2023-147883NB-C21, funded by MCIU/AEI/10.13039/501100011033. K.R. thanks the LSST-DA Data Science Fellowship Program, which is funded by LSST-DA, the Brinson Foundation and the Moore Foundation; their participation in the programme has benefited this work. A.T.D., R.M.S., Y.W., J.N.J.-S. and Y.W.J.L. acknowledge support through Australian Research Council Discovery Project DP220102305. Y.W. acknowledges support through Australian Research Council Future Fellowship FT190100155. R.T. acknowledges support from funding provided by the National Aeronautics and Space Administration (NASA), under award number 80NSSC20M0124, Michigan Space Grant Consortium (MSGC). F.W. was supported by the National Natural Science Foundation of China (grant numbers 12494575 and 12273009). Parts of this research were conducted by the Australian Research Council Centre of Excellence for Gravitational Wave Discovery (OzGrav), through project numbers CE170100004 and CE230100016.
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Authors and Affiliations
Contributions
Z. Wang and N.R. drafted the paper with suggestions from co-authors. E.L., Z. Wang, K.W.B. and Y.W. discovered the source. Z. Wang is the principal investigator of the MeerKAT data and the GMRT data. A.T.D. is the principal investigator of the VLBA data. T.M. is the principal investigator of the ATCA data (C3363). E.L., Z. Wang and A.A. further reduced the ASKAP data to produce dynamic spectra for detections and non-detections. Z. Wang and N.H.-W. reduced and analysed the MeerKAT imaging data. M.C. helped propose the MeerKAT observation and analyse MeerKAT data. M.G. reduced the MeerKAT H i data. Z. Wang, A.A., K.R., J.P. and Y.W. observed, reduced and analysed the ATCA data. A.B. and Z. Wang reduced and analysed the GMRT data. A.A. reduced the archival VLA data. T.E.C., W.M.P. and E.J.P. developed and maintained the VLITE data archive and performed the VLITE archive search, time slicing, imaging and cataloguing. A.T.D. reduced and analysed the VLBA data. D.L.K., S.K.O., V.K. and M.M.K. observed and analysed the infrared data. K.M. is the principal investigator of the Chandra data. T.B. and N.R. reduced and analysed the Chandra data. T.B. and N.R. reduced and analysed archival XMM-Newton and Swift data. N.R., D.L.K., Z. Wang and H.Q. helped in asking for the Einstein Probe data. N.R., as member of the Einstein Probe collaboration, reduced and analysed the Einstein Probe data. D.L.K., K.C.D. and R.T. performed multiwavelength archive searches. A.Z., S.J.M., D.L.K. and R.M.S. performed the radio timing analysis. A.Z. performed the radio polarimetry data reduction. J.R.D. performed H i absorption line analysis. N.H.-W. performed the SNR association analysis. R.M.S. performed the short-periodicity search. Z. Wadiasingh, J.H., A.J.C., P.B., G.Y., M.E.L., M.P.-T., F.W. and Z.Z. contributed to discussions about the nature and emission mechanism of the source. K.W.B., A.T.D., C.W.J. and R.M.S. are the principal investigators of CRACO. Z. Wang, M.G., Y.W., N.D.R.B., A.J., X.D., J.N.J.-S., Y.W.J.L., J.T. and N.T. contributed to the design and commissioning of CRACO. T.M. and D.L.K. are the principal investigators of VAST, and D.D. and L.N.D. are the project scientists of VAST. The principal investigators and builders of VAST and CRACO coordinated the initial investigation of the source.
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Extended data figures and tables
Extended Data Fig. 1 Field of ASKAP J1832–0911.
Panel (a) shows a composite of radio (MeerKAT 816 MHz, red), X-ray (Chandra 1–10 keV, green), and infrared (WISE 12 μm, blue) emission of the field of ASKAP J1832–0911. The Fermi 95% positional error ellipse around 4FGL J1832.9-0913 is shown in cyan dashed line. The supernovae remnant SNR G22.7–0.2 is highlighted in the yellow dotted line. Panel (b) shows MeerKAT total intensity contours at 30, 40, and 50 mJy levels overlaid on the Chandra detection image on 2024 February 14. Panel (c) and (d) show the deepest near-infrared images of ASKAP J1832–0911 at J- and Ks-band, respectively. Red circles show 50 times the systematic uncertainty of the source position (~5 mas).
Extended Data Fig. 2 Normalised LombScargle Periodogram for Chandra Observations on 2024 February 14.
Horizontal lines show the false alarm probabilities at 3σ (green), 2σ (orange), and 1σ (red). The purple vertical line shows the best frequency we fit from radio observations.
Extended Data Fig. 3 Upper limits on the quiescent X-ray luminosity as derived by XMM-Newton.
The 3σ X-ray luminosity limits are calculated as a function of photon index (Γ; panel a) and black body temperature (kT; panel b). We assume NH = 1.8 × 1022 cm−2, which is the Galactic column density in the direction of the source, consistent with the X-ray spectral fits during the outburst. The shaded region assumes the error in the distance (\({4.5}_{-0.5}^{+1.2}\) kpc).
Extended Data Fig. 4 Magneto-thermal evolutionary models for neutron stars assuming different initial magnetic-field strengths and configurations.
(a) Evolution in the \(P-\mathop{P}\limits^{.}\) plane. Dashed (solid) lines correspond to theoretical death lines for a pure dipole (highly multipolar) configuration18,19. The grey-shaded region indicates the radio pulsar ‘death valley’ between the two extreme configurations. (b) Evolution of the quiescent X-ray luminosity as a function of the rotational power (\(\mathop{E}\limits^{.}\)). The grey line is \({L}_{X}=\mathop{E}\limits^{.}\) while the grey shaded area represents the constraints for ASKAP J1832–0911 during quiescence. See10,77,78 and references therein for details on the theoretical cooling models and the plotted sources.
Extended Data Fig. 5 Quiescent X-ray luminosity as emitted thermally from the surface for different neutron star classes plotted as a function of age.
Circled stars are radio-emitting magnetars. We assume as a luminosity limit for the quiescent emission of ASKAP J1832–0911 that is derived from the deepest XMM-Newton limits on 2011-03-13, and the most recent limits derived after the outburst by Chandra on 2024-08-11 (light blue lines). Solid lines assume an X-ray spectrum modelled by a power law with Γ = 2, while dashed lines assume a blackbody with kT = 0.5 keV. The age refers to the age of the SNR when available, and to the characteristic age otherwise. See10 and Dehman, Marino, and Rea et al., manuscript in preparation for more details on the data extraction and sources.
Extended Data Fig. 6 Timing residuals for J1832-0911 assuming f = 3.7647183(4) × 10−4 s−1 and \(\mathop{{\boldsymbol{f}}}\limits^{.}={\bf{0}}\).
Uncertainties on the times of arrival have been adjusted in quadrature by EQUAD, fitted per-epoch, with values ranging from 6–69 s. The points are coloured by radio frequency, and the telescopes used for each measurement are indicated by the markers.
Extended Data Fig. 7 Constraints on the minimum distance for different stellar spectral types.
The purple line shows the spectral type limit we can constrain based on the current infrared observations.
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Supplementary Discussion, Figs. 1–8 and Table 1.
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Wang, Z., Rea, N., Bao, T. et al. Detection of X-ray emission from a bright long-period radio transient. Nature 642, 583–586 (2025). https://doi.org/10.1038/s41586-025-09077-w
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DOI: https://doi.org/10.1038/s41586-025-09077-w
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