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arXiv 1007.0463astro-ph.SR
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非球形核心坍缩超新星III。向同调的演化和对数值分辨率的依赖

Non-spherical core collapse supernovae III. Evolution towards homology and dependence on the numerical resolution

A. Gawryszczak, J. Guzman, T. Plewa, K. Kifonidis

摘要:

我们在二维空间中研究了非球形核坍缩超新星的流体动力学演化。我们发现,我们的模型显示出强烈的倾向,扩大向极点。我们证明,这种膨胀是低模式,SASI不稳定性的物理性质。SASI在后激波层中留下了一个大的横向速度梯度,影响了几分钟和几小时后的演变。这导致喷出物的长形变形和富镍物质从中纬度到极地地区的快速平流。这种效应实际上可能是造成SN 1987A中镍谱线整体不对称的原因。模拟结果表明,显着的径向和横向运动在后冲击区,产生的对流翻转和SASI在早期爆炸阶段,有助于冲击复兴后的几分钟和几个小时的演变。它们导致后来的团块形成,以及甚至在爆炸后一周观察到的喷出物的显著长形变形。正如Kjaer等人最近指出的那样,这种喷出物的形态与SN 1987A的观测数据吻合得很好。系统的未来的研究需要调查如何SASI引起的后期横向扩张取决于SASI的主导模式,以及在何种程度上它是由模拟的维数的影响。的影响和重要性的SASI的铁族核的分布和形态的年轻的SNR主张未来的三维爆炸和爆炸后的奇异性网格,覆盖整个球体的研究。鉴于我们的2D分辨率研究的结果,目前的3D模拟必须被视为欠分辨,他们的结论必须通过适当的数值收敛分析在三维验证。

英文摘要:

(abridged) We study the hydrodynamic evolution of a non-spherical core-collapse supernova in two spatial dimensions. We find that our model displays a strong tendency to expand toward the pole. We demonstrate that this expansion is a physical property of the low-mode, SASI instability. The SASI leaves behind a large lateral velocity gradient in the post shock layer which affects the evolution for minutes and hours later. This results in a prolate deformation of the ejecta and a fast advection of Ni-rich material from moderate latitudes to the polar regions. This effect might actually be responsible for the global asymmetry of the nickel lines in SN 1987A. The simulations demonstrate that significant radial and lateral motions in the post-shock region, produced by convective overturn and the SASI during the early explosion phase, contribute to the evolution for minutes and hours after shock revival. They lead to both later clump formation, and a significant prolate deformation of the ejecta which are observed even as late as one week after the explosion. As pointed out recently by Kjaer et al., such an ejecta morphology is in good agreement with the observational data of SN 1987A. Systematic future studies are needed to investigate how the SASI-induced late-time lateral expansion depends on the dominant mode of the SASI, and to which extent it is affected by the dimensionality of the simulations. The impact on and importance of the SASI for the distribution of iron group nuclei and the morphology of the young SNR argues for future three-dimensional explosion and post-explosion studies on singularity-free grids that cover the entire sphere. Given the results of our 2D resolution study, present 3D simulations must be regarded as underresolved, and their conclusions must be verified by a proper numerical convergence analysis in three dimensions.

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