Evolution of magnetic deformation in neutron star crust
Evolution of magnetic deformation in neutron star crust
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DOI：
10.1093/mnras/staa3489
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发表时间：
2020-11
影响因子：
4.8
通讯作者：
Y. Kojima;S. Kisaka;K. Fujisawa
中科院分区：
文献类型：
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作者：
Y. Kojima;S. Kisaka;K. Fujisawa
在这项研究中，我们研究的磁场演化发生在中子星星壳。在弹性极限之外，晶格离子被假定为塑性流动。在我们的数值模拟中考虑了欧姆耗散、霍尔漂移和洛伦兹力驱动的体流体速度。在地壳演化过程中，观测到了磁致四极形变。通常，椭圆率随着磁能的减小而减小。在超环面场主导的模型中，椭圆率的符号改变。也就是说，初始的长球形倾向于变成扁球形。这是因为环形分量在比极向偶极子分量更小的时间尺度上快速衰减。我们发现，磁偶极子组件不改变显着的霍尔时标$\sim 1$Myr考虑简单的初始模型。因此，需要一个更复杂的初始模型来研究上述时间尺度上的表面偶极子的快速衰减。
In this study, we examine the magnetic field evolution occurring in a neutron star crust. Beyond the elastic limit, the lattice ions are assumed to act as a plastic flow. The Ohmic dissipation, Hall drift, and bulk fluid velocity driven by the Lorentz force are considered in our numerical simulation. A magnetically induced quadrupole deformation is observed in the crust during the evolution. Generally, the ellipticity decreases as the magnetic energy decreases. In a toroidal-field-dominated model, the sign of the ellipticity changes. Namely, the initial prolate shape tends to become oblate. This occurs because the toroidal component decays rapidly on a smaller timescale than the poloidal dipole component. We find that the magnetic dipole component does not change significantly on the Hall timescale of $\sim 1$Myr for the considered simple initial models. Thus, a more complex initial model is required to study the fast decay of surface dipoles on the abovementioned timescale.