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

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

First listed 2025-09-18 | Last updated 2025-09-18

Abstract

Accretion discs 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 where radiation pressure is sufficient to unbind material from the inner disc ($L\gtrsim L_{\rm Edd}$). 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 ($L\gtrsim L_{\rm Edd}$). However, the wind is extremely slow, more consistent with the predictions of thermal-radiative winds launched by X-ray irradiation of the outer disc, than with the expected Eddington wind driven by radiation pressure from the inner disc. 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 ($v\sim 0.3c$) winds seen in recent Resolve observations of a supermassive black hole at similarly high Eddington ratio.

Short digest

XRISM/Resolve’s 2024-02-25 spectrum of the neutron-star binary GX 13+1 reveals a stratified, highly ionised, Compton-thick wind via dozens of narrow, slightly blueshifted lines from Si–Ni, including high-order Fe XXV/XXVI features above 7 keV. Photoionisation fits require a slow, very dense absorber plus a faster (~700 km/s), more ionised layer to reproduce the Fe XXVI Ly blue wing and residual core flux from wind reprocessing. After correcting for electron-scattering attenuation, the intrinsic luminosity is at or above Eddington, yet the outflow is extremely slow, favouring a thermal‑radiative outer-disc origin over an inner-disc radiation‑pressure (Eddington) wind. The contrast with ultrafast (~0.3c) SMBH winds at similar Eddington ratios points to fundamentally different launch mechanisms across mass scales.

Key figures to inspect

• Fig. 1 (Resolve spectrum): Inspect the forest of narrow H‑ and He‑like lines (Si–Ni) and the high‑order Fe XXV/XXVI transitions >7 keV; their small oscillator strengths yet large depths diagnose an extreme column and confirm the absorber is Compton‑thick while only slightly blueshifted.
• Fig. 2 (Historical variability): Compare the XRISM-coordinated NuSTAR spectrum with archival NuSTAR/RXTE; the unusually deep Fe XXV K edge at 8.8 keV and reduced flux identify the rare dense‑wind state (seen in only ~5–10% of RXTE epochs), while the blue band shows the intrinsic super‑Eddington continuum after τ_es co…
• Fig. 3 (Fe K zoom): The non‑black line cores require diffuse reprocessed/scattered emission from the wind, and the Fe XXVI Ly blue wing demands a faster (~700 km/s), broader (~300 km/s), more ionised component layered over the slow dense flow—direct evidence for wind stratification.
• Extended Data Fig. 5 (Ion fractions): The Fe ion balance shows only ~10% of Fe resides in Fe XXVI at the best‑fit ionisation, implying the fast-zone column is a lower limit because most Fe is fully stripped.