Inner crusts of neutron stars in strongly quantizing magnetic fields

Abstract

We study the ground-state properties of inner crusts of neutron stars in the presence of strong magnetic fields of ∼1017G. Nuclei coexist with a neutron gas and reside in a uniform gas of electrons in the inner crust. This problem is investigated within the Thomas-Fermi model. We extract the properties of nuclei based on the subtraction procedure of Bonche, Levit, and Vautherin. The phase space modification of electrons due to Landau quantization in the presence of strong magnetic fields leads to the enhancement of electron as well as proton fractions at lower densities of ∼0.001 fm-3. We find the equilibrium nucleus at each average baryon density by minimizing the free energy and show that, in the presence of strong magnetic fields, it is lower than that in the field-free case. The size of the spherical cell that encloses a nucleus along with the neutron and electron gases becomes smaller in strong magnetic fields compared to the zero-field case. Nuclei with larger mass and atomic numbers are obtained in the presence of strong magnetic fields compared with cases of zero field. © 2011. The American Astronomical Society. All rights reserved.