XRISM spectroscopy on orbital modulation of Fe Lyα lines in Cygnus X-3

Journal Article · Mon Jun 16 00:00:00 EDT 2025 · Publications of the Astronomical Society of Japan

DOI:https://doi.org/10.1093/pasj/psaf057· OSTI ID:2589569

Miura, Daiki ^[1]; Yamaguchi, Hiroya ^[2]; Ballhausen, Ralf ^[3]; Kallman, Timothy ^[4]; Enoto, Teruaki ^[5]; Yamada, Shinya ^[6]; Hakamata, Tomohiro ^[7]; Tomaru, Ryota ^[7]; Odaka, Hirokazu ^[7]; Hell, Natalie ^[8]; Nakajima, Hiroshi ^[9]; Watanabe, Shin ^[10]; Hayashi, Tasuku ^[6]; Kitamoto, Shunji ^[6]; Yamaoka, Kazutaka ^[11]; Miller, Jon M. ^[12]; Okabe, Keigo ^[13]; Maruzuka, Itsuki ^[13]; Koljonen, Karri ^[14]; McCollough, Mike ^[15]

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1. Univ. of Tokyo (Japan); Japan Aerospace Exploration Agency (ISAS/JAXA), Sagamihara, Kanagawa (Japan). Institute of Space and Astronautical Science
2. Japan Aerospace Exploration Agency (ISAS/JAXA), Sagamihara, Kanagawa (Japan). Institute of Space and Astronautical Science; Univ. of Tokyo (Japan); Aoyama Gakuin Univ., Sagamihara, Kanagawa (Japan)
3. Univ. of Maryland, College Park, MD (United States); NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
4. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
5. Kyoto Univ. (Japan)
6. Rikkyo Univ., Tokyo (Japan)
7. Osaka Univ. (Japan)
8. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
9. Kanto Gakuin Univ. Yokohama, Kanagawa (Japan)
10. Japan Aerospace Exploration Agency (ISAS/JAXA), Sagamihara, Kanagawa (Japan). Institute of Space and Astronautical Science
11. Nagoya Univ. (Japan)
12. Univ. of Michigan, Ann Arbor, MI (United States)
13. Aoyama Gakuin Univ., Sagamihara, Kanagawa (Japan)
14. Norwegian Univ. of Science and Technology, Trondheim (Norway)
15. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)

To understand physical processes such as mass transfer and binary evolution in X-ray binaries, the orbital parameters of the system are fundamental and crucial information. Cygnus X-3 is a high-mass X-ray binary composed of a compact object of unknown nature and a Wolf–Rayet star, which is of great interest in the context of wind-fed mass accretion and binary evolution. Here we present XRISM/Resolve high-resolution spectroscopy, focusing on the Fe Ly$$\alpha$$ lines when the source was in its hypersoft state. We perform an orbital phase-resolved spectral analysis of the lines to study the orbital modulation of the emission and absorption lines. It is found that the emission lines reflect the orbital motion of the compact object whose estimated velocity amplitude is $$430^{+150}_{-140}$$ km s$$^{-1}$$, while the absorption lines show a variation that can be interpreted as originating from the stellar wind. We discuss possible mass ranges for the binary components using the mass function with the estimated value of the velocity amplitude in this work, combined with the relation between the mass-loss rate and the orbital period derivative and the empirical mass and mass-loss rate relation for Galactic Wolf–Rayet stars. They are constrained to be (1.3–5.1) and (9.3–12) M$$_\odot$$, respectively, for the assumed inclination angle of $$i =25^\circ$$, and become more relaxed, (1.3–24) and (9.3–16) M$$_\odot$$, for $$i = 35^\circ$$. Thus, it remains unclear whether the system harbors a black hole or a neutron star.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: National Aeronautics and Space Administration (NASA); USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 2589569
• Journal Information: Publications of the Astronomical Society of Japan, Journal Name: Publications of the Astronomical Society of Japan Journal Issue: 1 Vol. 77; ISSN 0004-6264; ISSN 2053-051X
• Publisher: Oxford University Press (OUP)
• Country of Publication: United States
• Language: English

Related Subjects

X-rays: binaries
accretion
accretion disks
stars: Wolf–Rayet
stars: individual (Cygnus X-3)
stars: winds
outflows