Exploring the Physics of Dense Matter with Neutron Star Transients

Many accreting neutron stars do so intermittently; that is, the accretion ceases for long quiescent intervals. During the accretion outburst, reactions are induced in the crust by the continual accumulation of matter. These reactions heat the crust out of thermal equilibrium with the core, and when accretion stops and the system goes into quiescence, the thermal relaxation of the crust is detectable. This contribution gives a summary of recent theoretical and observational work interpreting the cooling lightcurves of these quasi-persistent transients. In particular, the lightcurves can constrain the core temperature of the neutron star, the thermal conductivity and heat capacity of the inner crust, and the distribution of heat sources in the outer crust.