Igoshev, AP orcid.org/0000-0003-2145-1022 and Hollerbach, R orcid.org/0000-0001-8639-0967 (2023) Three-dimensional numerical simulations of ambipolar diffusion in NS cores in the one-fluid approximation: instability of poloidal magnetic field. Monthly Notices of the Royal Astronomical Society, 518 (1). pp. 821-846. ISSN 0035-8711
Abstract
We numerically model evolution of magnetic fields inside a neutron star under the influence of ambipolar diffusion in the weak-coupling mode in the one-fluid MHD approximation. Our simulations are 3D and performed in spherical coordinates. Our model covers the neutron star core and includes crust where the magnetic field decay is due to Ohmic decay. We discover an instability of poloidal magnetic field under the influence of ambipolar diffusion. This instability develops in the neutron star core and grows on a time-scale of 0.2 dimensionless times, reaching saturation by 2 dimensionless times. The instability leads to formation of azimuthal magnetic field with azimuthal wavenumber m = 14 (at the moment of saturation) which keeps merging and reaches m = 4 by 16 dimensionless times. Over the course of our simulations (16 dimensionless times) the surface dipolar magnetic field decays, reaching 20 per cent of its original value and keeps decaying. The decay time-scale for the total magnetic energy is six dimensionless times. The ambipolar diffusion induces electric currents in the crust where these currents dissipate efficiently. Strong electric currents in the crust lead to heating, which could correspond to luminosities of ≈10²⁹ erg s¯¹during hundreds of Myrs for an initial magnetic field of 10¹⁴ G. Ambipolar diffusion leads to formation of small-scale magnetic fields at the neutron star surface.
Metadata
Item Type: | Article |
---|---|
Authors/Creators: |
|
Copyright, Publisher and Additional Information: | © 2022 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. |
Keywords: | magnetic fields, MHD, methods: numerical, stars: magnetic field, stars: neutron |
Dates: |
|
Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Mathematics (Leeds) > Applied Mathematics (Leeds) |
Funding Information: | Funder Grant number STFC (Science and Technology Facilities Council) ST/W000873/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 01 Nov 2022 12:37 |
Last Modified: | 25 Jun 2023 23:08 |
Status: | Published |
Publisher: | Oxford University Press |
Identification Number: | 10.1093/mnras/stac3126 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:192711 |