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arXiv · 2310.06697

Hard X-rays and QPO in Swift J1727.8-1613: the rise and plateau of the 2023 outburst

I. Mereminskiy·A. Lutovinov·S. Molkov·R. Krivonos·A. Semena·S. Sazonov·A. Tkachenko·R. Sunyaev
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Abstract

We report on the detection of type-C quasi-periodic oscillations during the initial stages of the outburst of Swift J1727.8-1613 in 2023. Using data of the INTEGRAL observatory along with the data of the SRG/ART-XC and Swift/XRT telescopes the fast growth of the QPO frequency was traced. We present a hard X-ray lightcurve that covers the initial stages of the 2023 outburst - the fast rise and plateau - and demonstrate that the QPO frequency was stable during the plateau. The switching from type-C to type-B QPO was detected with the beginning of the source flaring activity. We have constructed a broad-band spectrum of Swift J1727.8-1613 and found an additional hard power-law spectral component extending at least up to 400 keV. Finally, we have obtained an upper limit on the hard X-ray flux at the beginning of the optical outburst and estimated the delay of the X-ray outburst with respect to the optical one.

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I. Mereminskiy, A. Lutovinov, S. Molkov, R. Krivonos, A. Semena, S. Sazonov, A. Tkachenko, R. Sunyaev. 2023-10-10. Hard X-rays and QPO in Swift J1727.8-1613: the rise and plateau of the 2023 outburst. https://arxiv.org/abs/2310.06697

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