2017/09/30 by Taner Akgün, P. Cerdá–Durán, Pablo Cerdá-Durán +4 · 18 citations
Earth and Planetary Sciences · Engineering · Physics and Astronomy · #Astrophysics #Classical mechanics #Degenerate energy levels #Dipole #Field strength #Geophysics and Sensor Technology #Helicity #High-pressure geophysics and materials #Magnetar #Magnetic dipole #Magnetic field #Magnetic helicity #Magnetohydrodynamics #Neutron star #Physics #Pulsar #Pulsars and Gravitational Waves Research #Quantum electrodynamics #Quantum mechanics #astro-ph.HE
paper · pdf · doi:10.1093/mnras/stx2814
published in Monthly Notices of the Royal Astronomical Society 474(1), 625-635 (Oxford University Press) · 12 pages, 9 figures; added missing reference; accepted for publication in MNRAS
openalex publication_date 2017/10/28 · arxiv created 2018/10/10 · arxiv updated 2018/10/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We extend our previous study of equilibrium solutions of non-rotating force-free magnetospheres of neutron stars. We show that multiple solutions exist for the same sets of parameters, implying that the solutions are degenerate. We are able to obtain configurations with disconnected field lines, however, in nearly all cases these correspond to degenerate higher energy solutions. We carry out a wide parametric search in order to understand the properties of the solutions. We confirm our previous results that the lower energy solutions have up to ∼ 25 per cent more energy than the vacuum case, helicity of the order of ∼5 (in some defined units), maximum twist of ∼1.5 rad and a dipole strength that is up to ∼ 40 per cent larger than the vacuum dipole. Including the degenerate higher energy solutions allows for larger theoretical limits of up to ∼ 80 per cent more energy with respect to the vacuum case, helicity of the order of ∼8 and a dipole strength that can now be up to four times that of the vacuum dipole, while the twist can be significantly larger and even diverge for configurations with disconnected domains. The higher energy solutions are probably unstable, therefore, it is unlikely that such magnetospheres exist under normal conditions in magnetars and high magnetic field pulsars.