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arXiv · 2310.10444

Spectral Properties of GX~339--4 in the Intermediate State Using AstroSat Observation

Arghajit Jana·Debjit Chatterjee·Hsiang-Kuang Chang·Sachindra Naik·Santanu Mondal
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Abstract

We present the results obtained from the spectral studies of black hole X-ray binary GX~339--4 using \astrosat~ observations during its 2021 outburst. \astrosat~ observed the source in the intermediate state for $\sim600$ ks. The combined spectra of SXT and LAXPC in the $0.7-25$ keV energy range are studied with phenomenological and physical models. The spectral study reveals a receding disc and a contracting corona during the observation period. The outflow rate is found to be increased though the accretion rates did not vary during the observation period. The X-ray flux decreases as the disc recedes and the spectrum becomes hard. At the same time, the Comptonized flux decreases with increasing fraction of thermal emission. This could be plausible that episodic jet ejection modified the corona and reduced Comptonized flux. An iron emission line at 6.4 keV is observed in the spectra of all the orbits of observation. We find that the equivalent width of the iron emission line correlates with the photon index, indicating a decrease in the reflection strength as the spectrum becomes hard. We observe that the disc flux does not follow $F_{\rm DBB}-T^{4}$ relation.

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Arghajit Jana, Debjit Chatterjee, Hsiang-Kuang Chang, Sachindra Naik, Santanu Mondal. 2023-10-16. Spectral Properties of GX~339--4 in the Intermediate State Using AstroSat Observation. https://arxiv.org/abs/2310.10444

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