The thermal structure of the outer layers of accreting neutron stars impacts a number of astronomical observables, such as X-ray bursts, superbursts, and cooling transients following accretion turn-off. Electron capture reactions in the neutron star ocean and crust have the potential to remove or deposit substantial amounts of heat, with potential observational consequences. The presence and strength of electron capture-driven heating and (‘Urca’) cooling reactions in the outer layers of accreting neutron stars are primarily influenced by the properties of individual nuclei, many of which can be determined in the laboratory. In this presentation I will briefly discuss recent results regarding the impact of Urca cooling on X-ray superbursts and cooling transient neutron stars. I will show that Urca cooling pairs are likely ubiquitous throughout the accreted neutron star ocean and crust, and have the potential to substantially alter the light curve of cooling transient neutron stars and to shift the carbon ignition powering X-ray superbursts to deeper depths. Furthermore, I will highlight the present and future experimental efforts aimed at reducing the nuclear physics contribution to uncertainties in the presence and strength of Urca cooling pairs.
Argonne Physics Division Seminar Schedule