High-Energy Transients: Thermonuclear (Type-I) X-Ray Bursts

Many distinct classes of high-energy variability have been observed in astrophysical sources, and over a range of time-scales. The widest range, spanning microseconds to decades, is found in accreting, compact, stellar-mass objects, including neutron stars and black holes. Neutron stars are of particular observational interest as they exhibit surface effects giving rise to phenomena-such as thermonuclear bursts and pulsations-not seen in black holes. This talk reviewed briefly the present understanding of thermonuclear (Type-I) X-ray bursts-events that are powered by an extensive chain of nuclear reactions which in many cases are unique to the environments. Thermonuclear bursts have been exploited over the last few years as an avenue to measure a neutron star's mass and radius, although the contribution of systematic errors to the measurements remains contentious. We described recent efforts to match burst models to observations better, with a view to resolving some of the astrophysical uncertainties relating to those events. Our efforts have good prospects for providing information that is complementary to nuclear experiments.