Torsional oscillations of magnetized neutron stars with mixed poloidal-toroidal fields
Torsional oscillations of magnetized neutron stars with mixed poloidal-toroidal fields
复制标题
具有混合极向环形场的磁化中子星的扭转振荡
作者：
Gibran Henrique de Souza;C. Chirenti
在迄今为止观测到的软伽马射线中继器的三个巨大耀斑中发现的准周期振荡被解释为恒星磁场剧烈重排后星震引起的地壳振荡。受这些观测的启发，我们研究了磁场几何形状对磁化中子星扭转振荡频率的影响。我们使用现实的列表状态方程的核心和地壳的恒星和模型的磁场作为一个偶极子加上一个环形组件，使用相对论性的梯度-Shafranov方程。扭转模态的频率是由Cowling近似下的线性摄动方程所构成的特征值问题的数值解得到的。我们的研究结果表明，这些恒星的星震学变得复杂的退化的频率，由于大的相关参数空间。然而，我们能够提出一个可测试的场景，其中磁场的重排导致频率的演变。最后，我们表明，有一个磁场配置，最大限度地提高能量的扰动在线性秩序，这可能与触发的巨大耀斑。
The quasiperiodic oscillations found in the three giant flares of soft gamma-ray repeaters observed to date have been interpreted as crustal oscillations caused by a starquake following a dramatic rearrangement of the stellar magnetic field. Motivated by these observations, we study the influence of the magnetic field geometry in the frequencies of the torsional oscillations of magnetised neutron stars. We use realistic tabulated equations of state for the core and crust of the stars and model their magnetic field as a dipole plus a toroidal component, using the relativistic Grad-Shafranov equation. The frequencies of the torsional modes are obtained by the numerical solution of the eigenvalue problem posed by the linear perturbation equations in the Cowling approximation. Our results show how the asteroseismology of these stars becomes complicated by the degeneracy in the frequencies due to the large relevant parameter space. However, we are able to propose a testable scenario in which the rearrangement of the magnetic field causes an evolution in the frequencies. Finally, we show that there is a magnetic field configuration that maximizes the energy in the perturbation at linear order, which could be related to the trigger of the giant flare.
DOI：
10.1088/2041-8205/735/1/l20
发表时间：
2011-05
期刊：
The Astrophysical Journal Letters
影响因子：
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作者：
P. Lasky;B. Zink;K. Kokkotas;K. Glampedakis
通讯作者：
P. Lasky;B. Zink;K. Kokkotas;K. Glampedakis