Thermonuclear Bursts: Probing Neutron Stars and their Accretion Environments

Proposal abstract: Thermonuclear flashes on accreting neutron stars, observed as Type I X-ray bursts, offer a powerful probe of both how accreted material arrives and spreads over the surface of the neutron star and of the conditions inside the dense interior. We propose a combined observational and theoretical effort on two major outstanding issues in the physics of thermonuclear burning on neutron stars: photospheric radius expansion X-ray bursts and X-ray burst oscillations. Both of these phenomena have tremendous potential to measure neutron star masses and radii and thereby determine the equation of state of dense matter. Our goal is to enable this potential with new theoretical models aimed at understanding the basic physical processes of fuel accumulation and burning and the systematic uncertainties in deriving neutron star parameters.