Twisted magnetar magnetospheres

Ntotsikas, D., Gourgouliatos, K. N., Contopoulos, I. and Lander, S. K. (2024) Twisted magnetar magnetospheres. Monthly Notices of the Royal Astronomical Society, 527 (3). pp. 6691-6701. ISSN 0035-8711

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Abstract

Magnetar magnetospheres are strongly twisted, and are able to power sudden energetic events through the rapid release of stored electromagnetic energy. In this paper, we investigate twisted relativistic force-free axisymmetric magnetospheres of rotating neutron stars. We obtain numerical solutions of such configurations using the method of simultaneous relaxation for the magnetic field inside and outside the light-cylinder. We introduce a toroidal magnetic field in the region of closed field-lines that is associated with a poloidal electric current distribution in that region, and explore various mathematical expressions for that distribution. We find that, by increasing the twist, a larger fraction of magnetic field-lines crosses the light-cylinder and opens up to infinity, thus increasing the size of the polar caps and enhancing the spin-down rate. We also find that, for moderately to strongly twisted magnetospheres, the region of closed field-lines ends at some distance inside the light-cylinder. We discuss the implications of these solutions on the variation of magnetar spin-down rates, moding and nulling of pulsars, the relation between the angular shear and the twist, and the overall shape of the magnetosphere.

Item Type: Article
Additional Information: Funding Information: KNG acknowledges funding from grant FK 81641 ‘Theoretical and Computational Astrophysics’, ELKE, Special Account for Research Funds of the University of Patras.
Uncontrolled Keywords: methods: numerical,mhd,astronomy and astrophysics,space and planetary science ,/dk/atira/pure/subjectarea/asjc/3100/3103
Faculty \ School: Faculty of Science > School of Physics
Related URLs:
Depositing User: LivePure Connector
Date Deposited: 02 Jul 2024 12:32
Last Modified: 10 Jul 2024 01:53
URI: https://ueaeprints.uea.ac.uk/id/eprint/95761
DOI: 10.1093/mnras/stad3511

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