Computing the shear modulus of a multi-component neutron star crust.

Neutron stars are remnants of supernova that typically have a gravitational pull up to 10¹² m/s² . Due to this gravitational pull, the mass of the neutron star (comparable to that our sun), is compressed into an object with a radius of approximately 10 kilometers. Thus, neutron stars consist the densest matter in the known universe, making them optimal for studying fundamental forces in extreme environments. Neutron star crusts are a lattice structure of nuclei surrounded by a neutron gas. Most calculations only account for one species of nucleus existing at any given density. However, the likelihood is that there are multiple nuclear species at any given density (known as a multi-component crust) and that the median and spread of these nuclear sizes is dependent upon density and temperature. These affect mechanical properties such as the shear modulus which in turn affects predictions of observables such as modes of crust oscillations and oscillations between the crust and core. The distribution of the nuclei is computed at the freezing temperature of the crust assuming that the composition is then locked in as the star cools further. With this, we can calculate the shear modulus of a multi-component crust and compare it that of a one-component crust, thus estimating the systematic error present in using the one-component crust.