Speaker
Description
The timing analysis of X-ray binaries (XBs) is crucial for understanding the structure and dynamics governing these systems. Since the memorable 2023 outburst of the Low-Mass X-ray binary Swift J1727.8–1613, observations have been conducted across the entire electromagnetic spectrum, progressively constraining the source parameters. Here, we present the first XMM-Newton timing analysis of Swift J1727.8–1613 during the transition from the disk-dominated soft state to the hard state – dominated by the Comptonized emission from the hot plasma. When applying a multi-Lorentzian model to the power spectra (PS) and the Real and Imaginary parts of the cross spectra (CS), we identified quasi-periodic oscillations (QPOs) in the two harder observations, while no significant variability was observed in the softer observation. As the system approaches the hard state, the QPOs become narrower, shift to lower frequencies, and the rms amplitude in the PS increases in the 0.3–2 keV energy band. At the QPO frequency, the phase lags drop while the coherence function increases. All these features, previously observed in other XBs, suggest the presence of a type-C QPO.
| Affiliation | Astronomical Institute of the Czech Academy of Sciences |
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| maimouna.brigitte@asu.cas.cz |
