Core-Collapse Supernovae with Nonuniform Magnetic Fields
Core-Collapse Supernovae with Nonuniform Magnetic Fields
复制标题
具有不均匀磁场的核心塌缩超新星
DOI：
10.1086/432529
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
S. Yamada
中科院分区：
文献类型：
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作者：
H. Sawai;K. Kotake;S. Yamada
我们使用数字代码 ZEUS-2D 对具有强磁场和微分旋转的大质量恒星的核心塌缩进行二维数值模拟。通过参数化改变场配置和微分旋转定律，我们计算了 14 个模型并研究了这些参数对动力学的影响。在我们的模型中，我们没有解决中微子输运问题，而是采用了考虑中微子排放的唯象参数状态方程。计算结果表明，如果初始磁场足够大，磁场配置对核心动力学起着重要作用。最初具有集中场的模型比均匀场产生更多能量的爆炸和更多的长长冲击波。类四极场会产生非常准直且快速的射流，这对于伽马射线暴（GRB）可能很重要。在等离子体 β 小于 1 的区域中施加的洛伦兹力是造成这些动力学的原因。另一方面，纯环形场不会导致任何爆炸或物质喷射。这表明以环形场为主的前超新星模型对于此处考虑的磁旋转诱发超新星来说是不利的。最初磁场较弱的模型也不会导致爆炸或物质喷射。在这些模型中，磁场不起作用，因为它们不会在本文考虑的时间尺度上增长，并且磁压力可以与物质压力相当。这是因为在我们的模型中没有看到 MRI 中预期的指数场增长。在我们的模拟中，磁场主要通过场压缩和场包裹来放大。
We perform two-dimensional numerical simulations on the core collapse of a massive star with strong magnetic fields and differential rotations using the numerical code ZEUS-2D. Changing field configurations and laws of differential rotation parametrically, we compute 14 models and investigate the effects of these parameters on the dynamics. In our models we do not solve the neutrino transport but instead employ a phenomenological parametric EOS that takes into account the neutrino emissions. As a result of the calculations, we find that the field configuration plays a significant role in the dynamics of the core if the initial magnetic field is large enough. Models with initially concentrated fields produce more energetic explosions and more prolate shock waves than the uniform field. Quadrupole-like fields produce a remarkably collimated and fast jet, which might be important for gamma-ray bursts (GRBs). The Lorentz forces exerted in the region where the plasma β is less than unity are responsible for these dynamics. The pure toroidal field, on the other hand, does not lead to any explosion or matter ejection. This suggests that the presupernova models, in which toroidal fields are predominant are disadvantageous for the magnetorotation-induced supernova considered here. Models with initially weak magnetic fields do not lead to explosion or matter ejection, either. In these models magnetic fields play no role, as they do not grow on the timescale considered in this paper and the magnetic pressure could be comparable to the matter pressure. This is because the exponential field growth as expected in MRI is not seen in our models. The magnetic field is amplified mainly by field compression and field wrapping in our simulations.
巴塞尔大学（英国）
DOI：
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