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Magnetic field evolution in magnetar crusts through three-dimensional simulations

Lookup NU author(s): Dr Toby Wood

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This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).


Abstract

Current models of magnetars require extremely strong magnetic fields to explain their observed quiescent and bursting emission, implying that the field strength within the star’s outer crust is orders of magnitude larger than the dipole component inferred from spindown measurements. This presents a serious challenge to theories of magnetic field generation in a proto-neutron star. Here, we present detailed modelling of the evolution of the magnetic field in the crust of a neutron star through 3-D simulations. We find that, in the plausible scenario of equipartition of energy between global-scale poloidal and toroidal magnetic components, magnetic instabilities transfer energy to non-axisymmetric, kilometre-sized magnetic features, in which the local field strength can greatly exceed that of the global-scale field. These intense small-scale magnetic features can induce high energy bursts through local crust yielding, and the localised enhancement of Ohmic heating can power the star’s persistent emission. Thus, the observed diversity in magnetar behaviour can be explained with mixed poloidal-toroidal fields of comparable energies.


Publication metadata

Author(s): Gourgouliatos KN, Wood TS, Hollerbach R

Publication type: Article

Publication status: Published

Journal: Proceedings of the National Academy of Sciences

Year: 2016

Volume: 113

Issue: 15

Pages: 3944-3949

Print publication date: 12/04/2016

Online publication date: 28/03/2016

Acceptance date: 26/02/2016

ISSN (print): 0027-8424

ISSN (electronic): 1091-6490

Publisher: National Academy of Sciences

URL: http://dx.doi.org/10.1073/pnas.1522363113

DOI: 10.1073/pnas.1522363113

PubMed id: 27035962


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