Stratified wind from a super-Eddington X-ray binary is slower than expected

XRISM collaboration; Audard, Marc; Awaki, Hisamitsu; Ballhausen, Ralf; Bamba, Aya; Behar, Ehud; Boissay-Malaquin, Rozenn; Brenneman, Laura; Brown, Gregory V.; Corrales, Lia; Costantini, Elisa; Cumbee, Renata; Trigo, María Díaz; Done, Chris; Dotani, Tadayasu; Ebisawa, Ken; Eckart, Megan; Eckert, Dominique; Enoto, Teruaki; Eguchi, Satoshi; Ezoe, Yuichiro; Foster, Adam; Fujimoto, Ryuichi; Fujita, Yutaka; Fukazawa, Yasushi; Fukushima, Kotaro; Furuzawa, Akihiro; Gallo, Luigi; Garcia, Javier A.; Gu, Liyi; Guainazzi, Matteo; Hagino, Kouichi; Hamaguchi, Kenji; Hatsukade, Isamu; Hayashi, Katsuhiro; Hayashi, Takayuki; Hell, Natalie; Hodges-Kluck, Edmund; Hornschemeier, Ann; Ichinohe, Yuto; Ishida, Manabu; Ishikawa, Kumi; Ishisaki, Yoshitaka; Kaastra, Jelle; Kallman, Timothy; Kara, Erin; Katsuda, Satoru; Kanemaru, Yoshiaki; Kelley, Richard; Kilbourne, Caroline; Kitamoto, Shunji; Kobayashi, Shogo; Kohmura, Takayoshi; Kubota, Aya; Leutenegger, Maurice; Loewenstein, Michael; Maeda, Yoshitomo; Markevitch, Maxim; Matsumoto, Hironori; Matsushita, Kyoko; McCammon, Dan; McNamara, Brian; Mernier, François; Miller, Eric D.; Miller, Jon M.; Mitsuishi, Ikuyuki; Mizumoto, Misaki; Mizuno, Tsunefumi; Mori, Koji; Mukai, Koji; Murakami, Hiroshi; Mushotzky, Richard; Nakajima, Hiroshi; Nakazawa, Kazuhiro; Ness, Jan-Uwe; Nobukawa, Kumiko; Nobukawa, Masayoshi; Noda, Hirofumi; Odaka, Hirokazu; Ogawa, Shoji; Ogorzalek, Anna; Okajima, Takashi; Ota, Naomi; Paltani, Stephane; Petre, Robert; Plucinsky, Paul; Porter, Frederick Scott; Pottschmidt, Katja; Sato, Kosuke; Sato, Toshiki; Sawada, Makoto; Seta, Hiromi; Shidatsu, Megumi; Simionescu, Aurora; Smith, Randall; Suzuki, Hiromasa; Szymkowiak, Andrew; Takahashi, Hiromitsu; Takeo, Mai; Tamagawa, Toru; Tamura, Keisuke; Tanaka, Takaaki; Tanimoto, Atsushi; Tashiro, Makoto; Terada, Yukikatsu; Terashima, Yuichi; Tsuboi, Yohko; Tsujimoto, Masahiro; Tsunemi, Hiroshi; Tsuru, Takeshi G.; Tümer, Aysegül; Uchida, Hiroyuki; Uchida, Nagomi; Uchida, Yuusuke; Uchiyama, Hideki; Ueda, Yoshihiro; Uno, Shinichiro; Vink, Jacco; Watanabe, Shin; Williams, Brian J.; Yamada, Satoshi; Yamada, Shinya; Yamaguchi, Hiroya; Yamaoka, Kazutaka; Yamasaki, Noriko; Yamauchi, Makoto; Yamauchi, Shigeo; Yaqoob, Tahir; Yoneyama, Tomokage; Yoshida, Tessei; Yukita, Mihoko; Zhuravleva, Irina; Neilsen, Joey; Tomaru, Ryota; Mehdipour, Missagh

doi:10.1038/s41586-025-09495-w

Published October 2, 2025 | Version Published

Journal Article Open

Stratified wind from a super-Eddington X-ray binary is slower than expected

1. University of Geneva
2. Ehime University
3. University of Maryland, College Park
4. Goddard Space Flight Center
5. Center for Research and Exploration in Space Science and Technology
6. University of Tokyo
7. Technion – Israel Institute of Technology
8. Massachusetts Institute of Technology
9. University of Maryland, Baltimore
10. Harvard-Smithsonian Center for Astrophysics
11. Lawrence Livermore National Laboratory
12. University of Michigan–Ann Arbor
13. Netherlands Institute for Space Research
14. European Southern Observatory
15. Durham University
16. Institute of Space and Astronautical Science
17. Kyoto University
18. Kumamoto Gakuen University
19. Tokyo Metropolitan University
20. Hiroshima University
21. Fujita Health University
22. Saint Mary's University
23. California Institute of Technology
24. European Space Research and Technology Centre
25. University of Miyazaki
26. RIKEN Nishina Center, Saitama, Japan
27. Leiden University
28. Saitama University
29. Rikkyo University
30. Tokyo University of Science
31. Shibaura Institute of Technology
32. Osaka University
33. University of Wisconsin–Madison
34. University of Waterloo
35. Nagoya University
36. University of Teacher Education Fukuoka
37. Tohoku Gakuin University
38. Kanto Gakuin University
39. European Space Astronomy Centre
40. Kindai University
41. Nara University of Education
42. Tohoku University
43. Nara Women's University
44. Meiji University
45. Yale University
46. Konan University
47. Kagoshima University
48. Chuo University
49. Shizuoka University
50. Nihon Fukushi University
51. University of Amsterdam
52. RIKEN
53. Johns Hopkins University
54. University of Chicago
55. Villanova University
56. Space Telescope Science Institute

Accretion disks in strong gravity ubiquitously produce winds, seen as blueshifted absorption lines in the X-ray band of both stellar mass X-ray binaries (black holes and neutron stars) and supermassive black holes. Some of the most powerful winds (termed Eddington winds) are expected to arise from systems in which radiation pressure is sufficient to unbind material from the inner disk (L ≳ L_Edd). These winds should be extremely fast and carry a large amount of kinetic power, which, when associated with supermassive black holes, would make them a prime contender for the feedback mechanism linking the growth of those black holes with their host galaxies. Here we show the XRISM Resolve spectrum of the galactic neutron star X-ray binary, GX 13+1, which reveals one of the densest winds ever seen in absorption lines. This Compton-thick wind significantly attenuates the flux, making it appear faint, although it is intrinsically more luminous than usual (L ≳ L_Edd). However, the wind is extremely slow, more consistent with the predictions of thermal-radiative winds launched by X-ray irradiation of the outer disk than with the expected Eddington wind driven by radiation pressure from the inner disk. This puts new constraints on the origin of winds from bright accretion flows in binaries, but also highlights the very different origin required for the ultrafast (v ~ 0.3c) winds seen in recent Resolve observations of a supermassive black hole at a similarly high Eddington ratio.

Copyright and License

© The Author(s) 2025. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

Acknowledgement

This work was supported by the JSPS KAKENHI grant nos. JP24KJ0152, JP22H00158, JP22H01268, JP22K03624, JP23H04899, JP21K13963, JP24K00638, JP24K17105, JP21K13958, JP21H01095, JP23K20850, JP24H00253, JP21K03615, JP24K00677, JP20K14491, JP23H00151, JP19K21884, JP20H01947, JP20KK0071, JP23K20239, JP24K00672, JP24K17104, JP24K17093, JP20K04009, JP21H04493, JP20H01946, JP23K13154, JP19K14762, JP20H05857, JP23H01211, JP23K03454, JP23K22548, JP23K03459 and JP21H04493 and the NASA grant nos. 80NSSC24K1148, 80NSSC24K1774, 80NSSC18K0978, 80NSSC20K0883, 80NSSC20K0737, 80NSSC24K0678, 80NSSC18K1684, 80NSSC25K7064, 80NSSC23K0995, 80NSSC18K0988, 80NSSC23K1656 and 80NSSC23K0684. C.D. acknowledges support from the STFC through grant no. ST/T000244/1 and a Leverhulme Trust International Fellowship IF-2024-020. L.C. acknowledges support from the NSF (award no. 2205918). The material is based on the work supported by NASA under award no. 80GSFC21M0002. This work was supported by the JSPS Core-to-Core Program, JPJSCCA20220002. M.M. was supported by the Yamada Science Foundation. L.G. acknowledges financial support from the Canadian Space Agency (grant no. 18XARMSTMA). A.T. was supported in part by the Kagoshima University postdoctoral research program (KU-DREAM). S.Y. acknowledges support from the RIKEN SPDR Program. I.Z. acknowledges partial support from the Alfred P. Sloan Foundation through the Sloan Research Fellowship. Part of this work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under contract no. DE-AC52-07NA27344. The material was based on the work supported by the Strategic Research Center of Saitama University.

Data Availability

The XRISM Resolve data will be publicly available in the archives after the proprietary period ends. The NuSTAR dataset (ObsID 30901010002) is already publicly available.

Code Availability

The pion photoionization code is publicly available as part of the spex package. The warmabs photoionization code is publicly available as part of the xstar package. The ionabs code is publicly available for download at GitHub (https://github.com/ryotatomaru/Ionabs) as a local model for installation and use in the xspec package. The XSPEC model files used to make Extended Data Table 2, including the PION tables, are publicly available for download at Zenodo⁷⁰ (https://doi.org/10.5281/zenodo.15628497).

Supplemental Material

Extended Data Fig. 1 Mn Kα lines from the ⁵⁵Fe source in the filter wheel.

The black bins show the Hp spectrum extracted using two gain fiducial points, summing the 34 pixels. The blue line shows the intrinsic line profile, whereas the red one represents the best fit model, with additional Gaussian broadening of FWHM=4.43 eV. The lower panel shows the residuals between the data and the model, indicating that this is a good description.

Extended Data Fig. 2 Effective temperature of the calibration pixel versus time.

The effective temperature across the observation is shown as a solid black line, compared to a linear interpolation between the measurements at the start and end of the observation (blue dashed line). We introduce an ad-hoc gain point (red filled cicle, with a temperature ΔT_eff below the first gain point), to give a better match (red solid line).

Extended Data Fig. 3 Effective temperature variations in all pixels except 27.

Each pixel has an effective temperature estimate corresponding to the gain fiducial measurements at the beginning and end of the observation. We introduced an additional gain point by scaling the ad-hoc gain point from the calibration pixel (see Extended Data Fig. 2) to each individual pixel (see the middle point in each colored line). The black line shows the calibration pixel, which is tracked continuously, for reference.

Extended Data Fig. 4 Ion ratio as a function of ionisation parameter.

We computed the ground state populations for each ion using the pion code as in Methods. The ratio of these populations (equivalently, the ratio of the column densities in different ions) is sensitive to the ionisation parameter, as shown. Using the ratio of column densities taken from Extended Data Table 1, we estimate the ionisation parameter of the slow component in our ion-by-ion fits as (shaded regions), and the fast component of Fe and Ni as (shaded regions with black frames).

Extended Data Fig. 5 Ion fractions of Fe versus the ionisation parameter.

This is computed using pion as described in Methods, assuming that the gas is photoionised by the continuum shape observed. We estimate the ionisation parameter from our ion-by-ion fits using Extended Data Fig. 4, then used the curves above to determine the column density of completely-ionised Iron (Fe xxvii).

Extended Data Table 1 Fit with ion-by-ion absorption plus scattered flux.

Extended Data Table 2 Fit with two pion absorbers plus their emission and scattered flux.

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Additional details

PMID: 40963023
PMCID: PMC12488489

Describes: Journal Article: https://rdcu.be/eNwNH (ReadCube)
Is new version of: Discussion Paper: arXiv:2509.14555 (arXiv)
Is supplemented by: Software: https://github.com/ryotatomaru/Ionabs (URL); Dataset: 10.5281/zenodo.15628497 (DOI)

Japan Society for the Promotion of Science
JP24KJ0152
Japan Society for the Promotion of Science
JP22H00158
Japan Society for the Promotion of Science
JP22H01268
Japan Society for the Promotion of Science
JP22K03624
Japan Society for the Promotion of Science
JP23H04899
Japan Society for the Promotion of Science
JP21K13963
Japan Society for the Promotion of Science
JP24K00638
Japan Society for the Promotion of Science
JP24K17105
Japan Society for the Promotion of Science
JP21K13958
Japan Society for the Promotion of Science
JP21H01095
Japan Society for the Promotion of Science
JP23K20850
Japan Society for the Promotion of Science
JP24H00253
Japan Society for the Promotion of Science
JP21K03615
Japan Society for the Promotion of Science
JP24K00677
Japan Society for the Promotion of Science
JP20K14491
Japan Society for the Promotion of Science
JP23H00151
Japan Society for the Promotion of Science
JP19K21884
Japan Society for the Promotion of Science
JP20H01947
Japan Society for the Promotion of Science
JP20KK0071
Japan Society for the Promotion of Science
JP23K20239
Japan Society for the Promotion of Science
JP24K00672
Japan Society for the Promotion of Science
JP24K17104
Japan Society for the Promotion of Science
JP24K17093
Japan Society for the Promotion of Science
JP20K04009
Japan Society for the Promotion of Science
JP21H04493
Japan Society for the Promotion of Science
JP20H01946
Japan Society for the Promotion of Science
JP23K13154
Japan Society for the Promotion of Science
JP19K14762
Japan Society for the Promotion of Science
JP20H05857
Japan Society for the Promotion of Science
JP23H01211
Japan Society for the Promotion of Science
JP23K03454
Japan Society for the Promotion of Science
JP23K22548
Japan Society for the Promotion of Science
JP23K03459
Japan Society for the Promotion of Science
JP21H04493
National Aeronautics and Space Administration
80NSSC24K1148
National Aeronautics and Space Administration
80NSSC24K1774
National Aeronautics and Space Administration
80NSSC18K0978
National Aeronautics and Space Administration
80NSSC20K0883
National Aeronautics and Space Administration
80NSSC20K0737
National Aeronautics and Space Administration
80NSSC24K0678
National Aeronautics and Space Administration
80NSSC18K1684
National Aeronautics and Space Administration
80NSSC25K7064
National Aeronautics and Space Administration
80NSSC23K0995
National Aeronautics and Space Administration
80NSSC18K0988
National Aeronautics and Space Administration
80NSSC23K1656
National Aeronautics and Space Administration
80NSSC23K0684
Science and Technology Facilities Council
ST/T000244/1
Leverhulme Trust
IF-2024-020
National Science Foundation
2205918
National Aeronautics and Space Administration
80GSFC21M0002
Japan Society for the Promotion of Science
JPJSCCA20220002
Yamada Science Foundation
Canadian Space Agency
18XARMSTMA
Kagoshima University
RIKEN
Alfred P. Sloan Foundation
United States Department of Energy
DE-AC52-07NA27344
Saitama University

Accepted: 2025-08-05
Available: 2025-09-17

Published online

Caltech groups: Division of Physics, Mathematics and Astronomy (PMA)
Publication Status: Published

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Stratified wind from a super-Eddington X-ray binary is slower than expected

Copyright and License

Acknowledgement

Data Availability

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Stratified wind from a super-Eddington X-ray binary is slower than expected

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Abstract

Copyright and License

Acknowledgement

Data Availability

Code Availability

Supplemental Material

Files

s41586-025-09495-w.pdf

Files (8.4 MB)

Additional details

Identifiers

Related works

Funding

Dates

Caltech Custom Metadata