Speaker
Description
Thermonuclear X-ray bursts are observed from weakly magnetized neutron stars in low-mass X-ray binaries (LMXBs). In these systems, accreted material such as hydrogen and/or helium from a donor star undergoes unstable thermonuclear burning on the NS’s surface. These bursts typically show a fast rise for a few seconds, followed by an exponential decay for tens of seconds. Thermonuclear bursts strongly influence the nearby environment, including the accretion disk, corona and jet. While the immediate (~10s) and long-term (~days) behaviors after the burst have been extensively investigated, the intermediate timescale (~minutes) remains largely unexplored.
In this talk, I will present new observational evidence that thermonuclear bursts influence the accretion flow on the intermediate timescale. We find that in X-ray binary 4U 1820-30 the light curves after the bursts deviate from the exponential decay. The count rate fluctuates repeatedly on a time scale of minutes and returns to the pre-burst rate only after ~1000 seconds. The time-resolved spectroscopy using NICER data (0.2-10 keV) shows an anti-correlation between the flux of disk and corona, indicating different response to the burst irradiation. Complementary RXTE data (2-25 keV) further shows that the Fe K emission line, tracing the disk reflection, is also influenced by the burst, offering critical insight into the disk geometry. Our new approach can be applied to other bursting LMXBs, which serves as a powerful tool to probe the dynamic accretion flow in an unexplored timescale.
| Talk category | NOVA Network 3 |
|---|---|
| PhD relevance | 1st |
