Simulation of nuclear reactions within neutron stars outer crust using the compressible liquid drop model*

Simulating a single nucleus in a neutron star crust using the Compressible Liquid Drop model (CLDM), we can calculate how the composition of the nucleus changes as it sinks into the crust through three potential nuclear reactions: electron capture, neutron emission, and pycnonuclear fission. Determining which nuclear reactions occur in a neutron star crust involves calculating the energy released by each interaction under varying local conditions and assessing the most stable reaction. These reactions become more prominent as the pressure increases causing the nuclei to become more compact as we simulate deeper into the neutron star's crust. Using experimental element mass data in a CLDM, we evolve matter, starting at 56Fe, from the top of the neutron star’s crust to the base of the outer crust. Following which of the three prominent nuclear reactions occur at each depth allows us to analyze how the composition of the crust changes with depth along with the heat released by the nuclear reactions at each depth. Future work will focus on simulating how the uncertainty in the nuclear physics leads to uncertainty in heat released within the outer crust leading to uncertainties in the predicted temperature of low-mass x-ray binaries in quiescence, something we can measure.