Issue |
A&A
Volume 664, August 2022
|
|
---|---|---|
Article Number | A104 | |
Number of page(s) | 10 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361/202243769 | |
Published online | 10 August 2022 |
Simultaneous X-ray and optical spectroscopy of V404 Cygni supports the multi-phase nature of X-ray binary accretion disc winds
1
Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain
2
Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
e-mail: teo.munoz-darias@iac.es
3
INAF – Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate, LC, Italy
4
Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany
Received:
12
April
2022
Accepted:
26
May
2022
Observational signatures of accretion disc winds have been found in a significant number of low-mass X-ray binaries at either X-ray or optical wavelengths. The 2015 outburst of the black hole transient V404 Cygni provided a unique opportunity for studying both types of outflows in the same system. We used contemporaneous X-ray (Chandra Observatory) and optical (Gran Telescopio Canarias, GTC) spectroscopy, in addition to hard X-ray light curves (INTEGRAL). We show that the kinetic properties of the wind, as derived from P-Cyg profiles detected in the optical range at low hard X-ray fluxes and in a number of X-ray transitions during luminous flares, are remarkably similar. Furthermore, strictly simultaneous data taken at intermediate hard X-ray fluxes show consistent emission line properties between the optical and the X-ray emission lines, which most likely arise in the same accretion disc wind. We discuss several scenarios to explain the properties of the wind, favouring the presence of a dynamic, multi-phase outflow during the entire outburst of the system. This study, together with the growing number of wind detections with fairly similar characteristic velocities at different wavelengths, suggest that wind-type X-ray binary outflows might be predominantly multi-phase in nature.
Key words: accretion / accretion disks / stars: black holes / stars: winds / outflows / novae / cataclysmic variables
© T. Muñoz-Darias and G. Ponti 2022
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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