Effects of rare isotope reaction rates on the light curve of an X-ray burst

Abstract

X-ray bursts (XRBs) have been thought to occur via thermonuclear runaway reactions on the surface of a neutron star. The runaway reactions are affected by both the properties of the accreted material, such as the accretion rate and the composition, and the reaction rates of participating nuclei. We investigate how the shape of the XRB light curve changes with specific reaction rates. As a case study, we choose three reaction rates, triple alpha, 18Ne(α; ρ)21Na, and 15O(α; γ)19Ne. We find that the shape of the light curve does change with different reaction rates for the same reaction, but the predicted light curves with 54 isotopes do not match the observed ones even when the variations within the different reaction rates are considered. We confirm that the shape of the light curve is more sensitive to the number of isotopes that participate in the runaway reactions.