Magnetoelastic avalanches in magnetar crusts with plastic islands

Arthur G. Suvorov

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arXiv · 2610.33865

Magnetoelastic avalanches in magnetar crusts with plastic islands

Arthur G. Suvorov

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Abstract

High-energy outbursts from magnetars may be associated with crustal failures or quakes. The magnetoelastic modes of the star can be excited to large amplitudes in such a framework, providing a natural explanation for the quasi-periodic oscillations observed in the X-ray tails of some events. However, previous calculations of torsional modes have been carried out assuming an intact crust without accounting for the failure itself. We develop a code in this paper that solves the axial sector of the linearised Einstein-Maxwell-Euler equations in a cavity that hosts inelastic regions or 'plastic islands'. As crustal elements are displaced, shear stresses are tracked as a function of time to allow cells to dynamically switch from elastic to inelastic states. The presence of islands in the crust promotes phase mixing and, when reflected waves mix constructively, large sections fail collectively ('avalanche') if the initial kick is strong enough. Transient spectral features are observed as a result of the progressive loss of elastic support, which may explain the temperamental nature of the oscillations observed following giant flares and magnetar storms.

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Arthur G. Suvorov. 2026-10-24. Magnetoelastic avalanches in magnetar crusts with plastic islands. https://arxiv.org/abs/2610.33865

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