Magnetic neutron star equilibria with stratification and type II superconductivity
Abstract
We construct two-fluid equilibrium configurations for neutron stars (NSs) with magnetic fields, using a self-consistent and non-linear numerical approach. The two-fluid approach - likely to be valid for large regions of all but the youngest NSs - provides us with a straightforward way to introduce stratification and allows for more realistic models than the ubiquitous barotropic assumption. In all our models, the neutrons are modelled as a superfluid, whilst for the protons we consider two cases: one where they are a normal fluid and another where they form a type II superconductor. We consider a variety of field configurations in the normal-proton case and purely toroidal fields in the superconducting case. We find that stratification allows for a stronger toroidal component in mixed-field configurations, though the poloidal component remains the largest in all our models. We provide quantitative results for magnetic ellipticities of NSs, both in the normal- and superconducting-proton cases.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- January 2012
- DOI:
- 10.1111/j.1365-2966.2011.19720.x
- arXiv:
- arXiv:1106.6322
- Bibcode:
- 2012MNRAS.419..732L
- Keywords:
-
- MHD;
- stars: magnetars;
- stars: magnetic field;
- stars: neutron;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 21 pages, 14 figures