Issue |
A&A
Volume 698, June 2025
|
|
---|---|---|
Article Number | A166 | |
Number of page(s) | 9 | |
Section | Astrophysical processes | |
DOI | https://doi.org/10.1051/0004-6361/202555103 | |
Published online | 11 June 2025 |
Traces of wobbling accretion disk in X-ray pulsar Her X-1 from observations of the ART-XC telescope of the SRG observatory
1
Moscow State University, Sternberg Astronomical Institute, 119234 Moscow, Russia
2
Space Research Institute of the Russian Academy of Sciences, 117997 Moscow, Russia
⋆ Corresponding author: vlad.revnivtsev@cosmos.ru
Received:
10
April
2025
Accepted:
9
May
2025
Long uninterrupted observations of the X-ray binary system Her X-1 were performed with the Mikhail Pavlinsky ART-XC telescope of the Spectrum-Röntgen-Gamma (SRG) X-ray Observatory in the 4–25 keV energy range with total exposure of about two days around the main turn-on of the X-ray source. We present the results of the timing and spectral analysis of these observations. The opening of the X-ray source is determined to occur at the orbital phase ϕb ≈ 0.25. The analysis of the X-ray light curve reveals the first direct observational evidence of the nutation of a tilted precessing accretion disk with a period of ≃0.87 days. The appearance of X-ray pulsations near the orbital phase ϕb ≃ 0.77 prior to the main turn-on at the maximum of the nutation variability has also been detected. During the X-ray eclipse, a non-zero X-ray flux is measured, which is presumably associated with the scattering of X-ray emission in a hot corona around the optical star illuminated by the X-rays from the central neutron star. An increase in the X-ray flux after the main turn-on can be described by the passage of radiation from the central source through a scattering corona above the precessing accretion disk.
Key words: binaries: eclipsing / X-rays: individuals: Her X-1
© The Authors 2025
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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