Magnetically driven crustquakes in neutron stars

S. K. Lander, N. Andersson, D. Antonopoulou, A. L. Watts

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)2047-2058
Number of pages12
JournalMonthly Notices of the Royal Astronomical Society
Volume449
Issue number2
Early online date27 Mar 2015
DOIs
Publication statusPublished - May 2015
Externally publishedYes

Keywords

  • Asteroseismology
  • Stars: magnetars
  • Stars: magnetic field
  • Stars: neutron

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