Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/8243
Title: Flares during eclipses of high-mass X-ray binary systems Vela X-1, 4U 1700−37, and LMC X-4
Authors: Rikame, Ketan
Paul, Biswajit
Sharma, Rahul
Jithesh, V.
Paul, K.T.
Issue Date: 15-Mar-2024
Publisher: Oxford University Press on behalf of Royal Astronomical Society
Citation: Monthly Notices of the Royal Astronomical Society, 2024, Vol. 529, p3360
Abstract: In eclipsing X-ray binary systems, the direct X-ray emission is blocked by the companion star during the eclipse. We observe only reprocessed emission that contains clues about the environment of the compact object and its chemical composition, ionization levels, etc. We have found flares in some X-ray binaries during their eclipses. The study of eclipse flares provides additional clues regarding the size of the reprocessing region and helps distinguish between different components of the X-ray spectrum observed during the eclipse. In the archival data, we searched for flares during eclipses of high-mass X-ray binaries and found flares in three sources: Vela X-1, LMC X-4, and 4U 1700−37. Comparing spectral properties of the eclipse flare and non-flare data, we found changes in the power-law photon index in all three sources and multiple emission lines in Vela X-1 and 4U 1700-37. The fluxes of prominent emission lines showed a similar increase as the overall X-ray flux during the eclipse flare, suggesting the lines originate in the binary environment and not in the interstellar medium. We also observed a soft excess in 4U 1700-37 that remains unchanged during both eclipse flare and non-flare states. Our analysis suggests that this emission originates from the extremely thin shell of the stellar wind surrounding the photosphere of its companion star. The detection of short (100–200 s) count-rate doubling time-scale in 4U 1700−37 and LMC X-4 indicates that the eclipse reprocessing occurs in a region larger than, but comparable to the size of the companion star.
Description: Open Access
URI: http://hdl.handle.net/2289/8243
Alternative Location: https://ui.adsabs.harvard.edu/abs/2024arXiv240305936R/abstract
https://arxiv.org/abs/2403.05936
https://doi.org/10.1093/mnras/stae739
Copyright: 2024 The Author(s)
Appears in Collections:Research Papers (A&A)

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