Impact of Type I X-ray Bursts on Reflection Spectra from an Accretion Disk

Irradiation of the accretion disk causes reflection signatures in the spectrum, encoding important information such as the disk’s structure and density. A Type I X-ray burst will strongly irradiate the accretion disk and alter its properties. Previous numerical simulations predicted the evolution of the accretion disk due to an X-ray burst. Here, we employ the simulation data, which allows us for the first time to translate the disk’s evolution to changes in the reflection spectrum as the X-ray burst rises to its peak. For this purpose, we consider three different time intervals and compute the reflection spectrum for each. For each interval, we treat the accretion disk as a slab with a varying hydrogen number density that is irradiated from above and below. We partition the respective accretion disk into six zones. For each zone, we simulate a reflection spectrum and combine those to obtain the total reflection signature. As the peak rises, the irradiation and thus the ionization increases, leading to the weakening of reflection features. This work serves as the first testable prediction of time-dependent changes of the reflection spectrum due to an X-ray burst. The results will provide additional diagnostics for studying the accretion disk evolution due to a burst.