Issue |
A&A
Volume 690, October 2024
|
|
---|---|---|
Article Number | A148 | |
Number of page(s) | 11 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361/202348907 | |
Published online | 04 October 2024 |
X-ray view of emission lines in optical spectra: Spectral analysis of the two low-mass X-ray binary systems Swift J1357.2–0933 and MAXI J1305–704
1
Università degli Studi di Palermo, Dipartimento di Fisica e Chimica, Via Archirafi 36, 90123 Palermo, Italy
2
INAF/IASF Palermo, Via Ugo La Malfa 153, 90146 Palermo, Italy
3
IRAP, Universitè de Toulouse, CNRS, UPS, CNES, 9, Avenue du Colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
4
Department of Physics, University of Trento, Via Sommarive 14, 38122 Povo, TN, Italy
5
Dipartimento di Fisica, Università degli Studi di Cagliari, SP Monserrato-Sestu, KM 0.7, Monserrato 09042, Italy
6
Anton Pannekoek Institute for Astronomy, University of Amsterdam, Postbus 94249, 1090 GE Amsterdam, The Netherlands
7
Department of Astronomy, The University of Michigan, 1085 South University Avenue, Ann Arbor, MI 48109, USA
Received:
11
December
2023
Accepted:
22
July
2024
We propose a novel approach for determining the orbital inclination of low-mass X-ray binary systems by modelling the Hα and Hβ line profiles emitted by the accretion disc, with a Newtonian (i.e. non-relativistic) version of DISKLINE. We applied the model to two sample sources, Swift J1357.2–0933 and MAXI J1305–704, which are both transient black hole systems, and analyse two observations that were collected during a quiescent state and one observation of an outburst. The line profile is well described by the DISKLINE model, although we had to add a Gaussian line to describe the deep inner core of the double-peaked profile, which the DISKLINE model was unable to reproduce. The Hβ emission lines in the spectrum of Swift 1357.2–0933 and the Hα emission lines in that of MAXI J1305–704 during the quiescent state are consistent with a scenario in which these lines originate from a disc ring between (9.6 − 57)×103 Rg and (1.94 − 20)×104 Rg, respectively. We estimate an inclination angle of 81 ± 5 degrees for Swift J1357.2−0933 and an angle of 73 ± 4 degrees for MAXI J1305−704. This is entirely consistent with the values reported in the literature. In agreement with the recent literature, our analysis of the outburst spectrum of MAXI J1305−704 revealed that the radius of the emission region deviates from expected values. It is larger than the orbital separation of the system. This outcome implies several potential scenarios, including line profile contamination, an alternative disc configuration that deviates from the Keplerian model, or even the possibility of a circumbinary disc. We caution that these results were derived from a simplistic model that may not fully describe the complicated physics of accretion discs. Despite these limitations, our results for the inclination angles are remarkably consistent with recent complementary studies, and the proposed description of the emitting region remains entirely plausible.
Key words: accretion / accretion disks / line: profiles / stars: black holes / X-rays: binaries / X-rays: individuals: Swift J1357.2–0933 / X-rays: individuals: MAXI J1305–704
© The Authors 2024
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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