Improving Microscopic Models of the Neutron Star Crust


Shuxi Wang

Document Type


Degree Name

Master of Science (MS)


Physics and Astronomy

Date of Award

Summer 2015


The task of understanding the properties of neutron stars has attracted the attention of researchers in different fields, such as astronomy and nuclear and condensed matter physics. In this thesis, we focus on a region of matter called the nuclear ``pasta phases,'' exotic nuclear geometries which occur at the transition from the bottom of the inner crust to the super-dense core of the neutron star. There are two simulation models applied in this work; one is the Three Dimensional Hartree Fock (3DHF) model, and the other is the Compressible Liquid Drop Model (CLDM). The Hartree Fock method is the most accurate way to simulate nuclear matter in recent times but is time-consuming and contains spurious numerical effects. On the other hand, the Liquid Drop Model is efficient but oversimplifies the physics. The CLDM method treats nuclear matter as a ``droplet'' of nuclear matter, which loses sight of the behavior of each nucleon and the interaction between them. The 3DHF model provides a more microscopic description of crustal matter in the neutron star. In this thesis we aimed to combine the advantages of both methods. We aimed to (i) devise a way of subtracting the spurious numerical effects from the results of 3DHF calculations, and then (ii) fit the results from the CLDM model to those of the 3DHF model by varying the parameters that determine the surface tension of nuclei in the model. This allowed the CLDM to accurately predict the composition of the inner crust and the 3DHF model to do precise calculations of crustal properties given that composition.


William Newton

Subject Categories

Physical Sciences and Mathematics | Physics