[论文解读] Recent Progress on Ascertaining the Core Collapse Supernova Explosion Mechanism

Anthony Mezzacappa, Stephen W. Bruenn+9 more|arXiv (Cornell University)|Jan 7, 2015

Neutrino Physics Research参考文献 1被引用 9

一句话总结

本文综述了利用多维、多物理场模拟在核心坍缩超新星建模方面的最新进展，表明中微子驱动对流与驻波激波不稳定性（SASI）共同作用可在二维轴对称模型中实现稳定的爆炸。首次的三维模拟显示出希望，表明中微子加热、湍流与非对称性可能共同克服激波停滞，标志着解决长期存在的爆炸机制难题迈出了关键一步。

ABSTRACT

We have been working within the fundamental paradigm that core collapse supernovae (CCSNe) may be neutrino driven, since the first suggestion of this by Colgate and White nearly five decades ago. Computational models have become increasingly sophisticated, first in one spatial dimension assuming spherical symmetry, then in two spatial dimensions assuming axisymmetry, and now in three spatial dimensions with no imposed symmetries. The increase in the number of spatial dimensions has been accompanied by an increase in the physics included in the models, and an increase in the sophistication with which this physics has been modeled. Computation has played an essential role in the development of CCSN theory, not simply for the obvious reason that such multidimensional, multi-physics, nonlinear events cannot possibly be fully captured analytically, but for its role in discovery. In particular, the discovery of the standing accretion shock instability (SASI) through computation about a decade ago has impacted all simulations performed since then. Today, we appear to be at a threshold, where neutrinos, neutrino-driven convection, and the SASI, working together over time scales significantly longer than had been anticipated in the past, are able to generate explosions, and in some cases, robust explosions, in a number of axisymmetric models. But how will this play out in three dimensions? Early results from the first three-dimensional (3D), multi-physics simulation of the "Oak Ridge" group are promising. I will discuss the essential components of today's models and the requirements of realistic CCSN modeling, present results from our one-, two-, and three-dimensional models, place our models in context with respect to other efforts around the world, and discuss short- and long-term next steps.

研究动机与目标

• 调查中微子驱动对流与驻波激波不稳定性（SASI）是否能在多维模拟中驱动核心坍缩超新星的稳定爆炸。
• 评估多维流体动力学、中微子输运与湍流在克服大质量恒星核心激波停滞中的作用。
• 评估前身星非球对称性与改进初始条件对三维模拟中爆炸可行性的影响。
• 探讨缺失的物理效应——特别是中微子质量效应与先进输运——是否对成功模拟爆炸至关重要。
• 确定当前计算模型，尤其是三维模型，能否再现观测到的爆炸能量（约1–5贝特）与物理机制。

提出的方法

• 采用Chimera代码进行核心坍缩超新星的多物理场、多维模拟，使用隐式时间积分与高分辨率有限体积方法。
• 在激波后区域采用通量限制扩散近似进行中微子输运，考虑能量与角度相关的中微子发射与吸收。
• 在PROMETHEUS-VERTEX框架中实现多组分状态方程与基于Tolman-Oppenheimer-Volkov的单极校正自洽引力。
• 在三维空间中进行模拟，逐步增加物理复杂性与空间分辨率。
• 在不同代码（如PROMETHEUS-VERTEX、COCONUT-VERTEX）与前身星模型之间进行对比，包括Woosley–Heger前身星模型及其三维恒星演化偏差。
• 分析SASI、中微子驱动对流与湍流压力在驱动激波膨胀中的相互作用。

实验结果

研究问题

• RQ1 中微子驱动对流与SASI是否能在核心坍缩超新星的二维与三维模拟中共同产生稳定且高能的爆炸？
• RQ2 前身星模型偏离球对称性如何影响多维模拟中爆炸的启动与持续性？
• RQ3 当前中微子输运与流体动力学中的近似在多大程度上限制了爆炸模拟的成功？
• RQ4 湍流动压在激波膨胀中起什么作用，其与中微子加热产生的热压相比如何？
• RQ5 中微子质量效应与中微子输运中的相干量子过程是否可能在未来模型中从根本上改变爆炸机制？

主要发现

• 在包含中微子驱动对流与SASI的二维轴对称模拟中成功生成了爆炸，表明多维效应对激波复兴至关重要。
• 奥克 Ridge 团队首次开展的三维多物理场模拟显示出有希望的结果，表明复杂流体不稳定性可在无需强初始非对称性的情况下驱动爆炸。
• SASI模态，特别是m=1螺旋模态，可引起显著剪切与湍流，从而从长波模式中抽取能量，可能限制其增长。
• 湍流动压可能对向外驱动激波有显著贡献，从而减轻对中微子加热的单一依赖。
• 具有三维偏离球对称性的前身星模型——如来自先进恒星演化模拟的模型——可在原本不会爆炸的模型中触发爆炸。
• 当前模拟表明，去除中微子输运中的近似并提高空间分辨率，可能是实现与观测爆炸能量定量一致的必要条件。