Broadband X-ray Spectral and Timing Analyses of the Black Hole Binary Candidate Swift J1658.2-4242: Rapid Flux Variation and the Turn-on of a Transient QPO

Abstract

We report results from joint NuSTAR, Swift and XMM-Newton observations of the newly discovered black hole X-ray binary candidate Swift J1658.2-4242 in the intermediate state. We observe a peculiar event in this source, with its X-ray flux rapidly decreasing by $\sim$45\% in $\sim$40~s, accompanied by only subtle changes in the shape of the broadband X-ray spectrum. In addition, we find a sudden turn-on of a transient QPO with a frequency of $6-7$~Hz around the time of the flux change, and the total fractional rms amplitude of the power spectrum increases from $\sim$2\% to $\sim$10\%. X-ray spectral and timing analyses indicate that the flux decrease is driven by intrinsic changes in the accretion flow around the black hole, rather than intervening material along the line of sight. In addition, we do not significantly detect any relativistic disk reflection component, indicating it is much weaker than previously observed while the source was in the bright hard state. We propose accretion disk instabilities triggered at a large disk radius as the origin of the fast transition in spectral and timing properties, and discuss possible causes of the unusual properties observed in Swift J1658.2-4242. The prompt flux variation detected along with the emergence of a QPO makes the event an interesting case for investigating QPO mechanisms in black hole X-ray binaries.

accepted for publication in ApJ

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Cited by in corpus (10)

• NICER uncovers the transient nature of the type-B quasi-periodic oscillation in the black hole candidate MAXI J1348-630
• Spectral and Timing Properties of the Galactic X-ray transient Swift~J1658.2--4242 using Astrosat Observations
• Wavelet analysis of MAXI J1535-571 with Insight-HXMT
• An underlying clock in the extreme flip-flop state transitions of the black hole transient Swift J1658.2-4242
• Spectro-temporal studies of rapid transition of the quasi periodic oscillations in the black hole source H1743-322
• Fast transitions of X-ray variability in the black hole transient GX 339--4: comparison with MAXI J1820+070 and MAXI J1348-630
• MAXI J1820+070 with NuSTAR II. Flaring during the hard to soft state transition with a long soft lag
• Wavelet analysis of the transient QPOs in MAXI J1535$-$571 with Insight-HXMT
• Spectral and Temporal Studies of Swift\,J1658.2--4242 using {\it AstroSat} Observations with {\tt JeTCAF} Model
• Multiwavelength study of 1eRASS J085039.9-421151 with eROSITA NuSTAR and X-shooter