Soft X-ray emission lines in the X-ray binary Swift J1858.6-0814 observed with XMM-Newton-RGS: Disc atmosphere or wind?

Buisson, D. J. K., Altamirano, D., Díaz Trigo, M., Mendez, M., Armas Padilla, M., Castro Segura, N., Degenaar, N. D., van den Eijnden, J., Fogantini, F. A., Gandhi, P., Knigge, C., Muñoz-Darias, T., Arabacı, M. Ö. & Vincentelli, F. M., Oct-2020, In : Monthly Notices of the Royal Astronomical Society. 498, 1, p. 68-76

Research output: Contribution to journalArticleAcademicpeer-review

  • D. J. K. Buisson
  • D. Altamirano
  • M. Díaz Trigo
  • M. Mendez
  • M. Armas Padilla
  • N. Castro Segura
  • N. D. Degenaar
  • J. van den Eijnden
  • F. A. Fogantini
  • P. Gandhi
  • C. Knigge
  • T. Muñoz-Darias
  • M. Özbey Arabacı
  • F. M. Vincentelli
We find soft X-ray emission lines from the X-ray binary Swift J1858.6-0814 in data from XMM-Newton-RGS: N VII, O VII and O VIII, as well as notable residuals short of a detection at Ne IX and other higher ionisation transitions. These could be associated with the disc atmosphere, as in accretion disc corona sources, or with a wind, as has been detected in Swift J1858.6-0814 in emission lines at optical wavelengths. Indeed, the N VII line is redshifted, consistent with being the emitting component of a P-Cygni profile. We find that the emitting plasma has an ionisation parameter log (ξ) = 1.35 ± 0.2 and a density n > 1.5 × 1011 cm-3. From this, we infer that the emitting plasma must be within 1013 cm of the ionising source, ∼5 × 107rg for a 1.4M⊙ neutron star, and from the line width that it is at least 104rg away (2 × 109(M/1.4M⊙) cm). We compare this with known classes of emission line regions in other X-ray binaries and active galactic nuclei.
Original languageEnglish
Pages (from-to)68-76
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Early online date1-Aug-2020
Publication statusPublished - Oct-2020


  • accretion, accretion discs, X-rays: binaries, black hole physics, stars: neutron

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