Neutron Star Crust in Strong Magnetic Fields

TL;DR

This paper investigates how strong magnetic fields influence the structure, composition, and stability of neutron star crusts, revealing the emergence of new nuclei and altered phase coexistence, with implications for magnetar properties.

Contribution

It provides a detailed analysis of the effects of intense magnetic fields on neutron star crust nuclei using updated nuclear data and models, highlighting new nuclear sequences and stability conditions.

Findings

New nuclei appear in the crust at B~10^{16}G.

Nuclei with larger mass numbers are stable at B~10^{17}G.

Proton density and phase coexistence are significantly affected by magnetic fields.

Abstract

We discuss the effects of strong magnetic fields through Landau quantization of electrons on the structure and stability of nuclei in neutron star crust. In strong magnetic fields, this leads to the enhancement of the electron number density with respect to the zero field case. We obtain the sequence of equilibrium nuclei of the outer crust in the presence of strong magnetic fields adopting most recent versions of the experimental and theoretical nuclear mass tables. For $B\sim 10^{16}$G, it is found that some new nuclei appear in the sequence and some nuclei disappear from the sequence compared with the zero field case. Further we investigate the stability of nuclei in the inner crust in the presence of strong magnetic fields using the Thomas-Fermi model. The coexistence of two phases of nuclear matter - liquid and gas, is considered in this case. The proton number density is significantly enhanced in strong magnetic fields $B\sim 10^{17}$G through the charge neutrality. We find nuclei with larger mass number in the presence of strong magnetic fields than those of the zero field. These results might have important implications for the transport properties of the crust in magnetars.