Magnetically driven crustquakes in neutron stars

Lander, S. K., Andersson, N., Antonopoulou, D. and Watts, A. L. (2015) Magnetically driven crustquakes in neutron stars. Monthly Notices of the Royal Astronomical Society, 449 (2). pp. 2047-2058. ISSN 0035-8711

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Abstract

Crustquake events may be connected with both rapid spin-up 'glitches' within the regular slowdown of neutron stars, and high-energy magnetar flares. We argue that magnetic-field decay builds up stresses in a neutron star's crust, as the elastic shear force resists the Lorentz force's desire to rearrange the global magnetic-field equilibrium.We derive a criterion for crustbreaking induced by a changing magnetic-field configuration, and use this to investigate strain patterns in a neutron star's crust for a variety of different magnetic-fieldmodels. Universally,we find that the crust is most liable to break if the magnetic field has a strong toroidal component, in which case the epicentre of the crustquake is around the equator. We calculate the energy released in a crustquake as a function of the fracture depth, finding that it is independent of field strength. Crust-breaking is, however, associated with a characteristic local field strength of 2.4 × 1014 G for a breaking strain of 0.001, or 2.4 × 1015 G at a breaking strain of 0.1. We find that even the most luminous magnetar giant flare could have been powered by crustal energy release alone.

Item Type: Article
Uncontrolled Keywords: asteroseismology,stars: magnetars,stars: magnetic field,stars: neutron,astronomy and astrophysics,space and planetary science ,/dk/atira/pure/subjectarea/asjc/3100/3103
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Depositing User: LivePure Connector
Date Deposited: 28 Jan 2020 03:52
Last Modified: 22 Apr 2020 08:34
URI: https://ueaeprints.uea.ac.uk/id/eprint/73804
DOI: 10.1093/mnras/stv432

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