A superburst's impact on the accretion disk around the neutron star in 4U 1636-536
Abstract
Superbursts are thought to be produced by a thermonuclear flash near the bottom of the carbon-rich ocean of accreting neutron stars. Lasting several hours, they allow for much more detailed X-ray spectra than the minute-long Type I X-ray bursts frequently observed from the same systems. Superbursts are, however, rare. We use one of only two detailed superburst observations to investigate changes in the accretion disk under the influence of the powerful burst. We find a doubling of the flux of the non-thermal spectral component that is often associated with the accretion process. Furthermore, thermal emission from the neutron star surface reflects off the accretion disk. Fits with detailed reflection models suggest a change in the ionization state of the reflecting material during the tail of the superburst. We discuss the consequences of the extra non-thermal flux and the reflection component for the interpretation of observations of both superbursts and the short X-ray bursts, which are used as probes for the unique nuclear physics deeper inside the neutron star.
- Publication:
-
AAS/High Energy Astrophysics Division #14
- Pub Date:
- August 2014
- Bibcode:
- 2014HEAD...1412227K