用扩展参考系模拟超新星遗迹中三维瑞利-泰勒不稳定性的增长
Simulation of the growth of the 3D Rayleigh-Taylor instability in Supernova Remnants using an expanding reference frame
摘要：
内容：由超新星遗迹在喷出物占主导地位的阶段减速产生的瑞利-泰勒不稳定性，已知会在物质分布中产生指状结构，从而修改遗迹的几何形状。超新星遗迹的形态也有望被修改时，有效的粒子加速发生在他们的冲击。目的：本文研究了在超新星遗迹的一个八分圆范围内，从抛射物为主到Sedov-Taylor相的瑞利-泰勒不稳定性的影响。我们还研究了在前向激波处有效粒子加速对瑞利-泰勒不稳定性增长的影响。研究方法：我们修改了自适应网格精化程序RAMSES，在扩展参考系的框架下，用流体动力学数值模拟研究了超新星遗迹的演化。前向激波和接触间断之间的相对论气体的绝热指数模拟了加速粒子的存在。结果如下：这里采用的超共动坐标系的最大优点是，由于它相对于网格是静止的，所以它使接触不连续处的数值扩散最小化。我们提出了一个准确的表达式的瑞利-泰勒结构的增长，顺利连接早期增长的渐近自相似行为。结论：如果冲击波由宇宙射线主导，瑞利-泰勒结构的发展受到影响，尽管不是很大。在后一种情况下，进入受冲击的星际介质的喷出物数量较少。如果两个冲击都发生加速度，则瑞利-泰勒结构的范围相似，但反向冲击受到强烈扰动。
英文摘要：
Context: The Rayleigh-Taylor instabilities generated by the deceleration of a supernova remnant during the ejecta-dominated phase are known to produce finger-like structures in the matter distribution which modify the geometry of the remnant. The morphology of supernova remnants is also expected to be modified when efficient particle acceleration occurs at their shocks. Aims: The impact of the Rayleigh-Taylor instabilities from the ejecta-dominated to the Sedov-Taylor phase is investigated over one octant of the supernova remnant. We also study the effect of efficient particle acceleration at the forward shock on the growth of the Rayleigh-Taylor instabilities. Methods: We modified the Adaptive Mesh Refinement code RAMSES to study with hydrodynamic numerical simulations the evolution of supernova remnants in the framework of an expanding reference frame. The adiabatic index of a relativistic gas between the forward shock and the contact discontinuity mimics the presence of accelerated particles. Results: The great advantage of the super-comoving coordinate system adopted here is that it minimizes numerical diffusion at the contact discontinuity, since it is stationary with respect to the grid. We propose an accurate expression for the growth of the Rayleigh-Taylor structures that connects smoothly the early growth to the asymptotic self-similar behaviour. Conclusions: The development of the Rayleigh-Taylor structures is affected, although not drastically, if the blast wave is dominated by cosmic rays. The amount of ejecta that makes it into the shocked interstellar medium is smaller in the latter case. If acceleration occurs at both shocks the extent of the Rayleigh-Taylor structures is similar but the reverse shock is strongly perturbed.
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