2023/10/10 by I. A. Mereminskiy, Mereminskiy, I., A. Lutovinov +13 · 4 citations
Physics and Astronomy · Engineering · #Astrophysical Phenomena and Observations #Gamma-ray bursts and supernovae #Astronomical Observations and Instrumentation
paper · pdf · doi:10.48550/arxiv.2310.06697
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.