Speaker
Description
Type-I thermonuclear bursts (TNBs) in neutron star low-mass X-ray binaries arise from unstable nuclear burning on the neutron star surface, whereas kHz quasi-periodic oscillations (QPOs) are believed to originate in the innermost regions of the accretion disk. The intense radiation released during a Type-I burst can perturb the inner accretion flow and thereby affect the kHz QPOs. Using 3–20 keV observations of 4U 1636−536 from AstroSat, we investigated the evolution of both upper and lower kHz QPOs around Type-I bursts. kHz QPOs were detected up to 200 s before burst onset but disappeared for approximately 100–200 s afterwards, reappearing only after ~200 s. This suppression is accompanied by a ~5–6% decrease in fractional rms amplitude, indicating a temporary disappearance of the QPO signal. The recovery timescale is comparable to the viscous timescale of the inner disk, suggesting that burst radiation temporarily disrupts the inner accretion flow, with the kHz QPOs re-establishing once the disk structure is restored.