Two-Dimensional Multiangle, Multigroup Neutrino Radiation-Hydrodynamic Simulations of Postbounce Supernova Cores
Two-Dimensional Multiangle, Multigroup Neutrino Radiation-Hydrodynamic Simulations of Postbounce Supernova Cores
复制标题
弹跳后超新星核心的二维多角度、多群中微子辐射-流体动力学模拟
DOI：
10.1086/591440
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
E. Livne
中科院分区：
文献类型：
--
作者：
C. Ott;A. Burrows;L. Dessart;E. Livne
我们使用真正的 2D 离散坐标 (Sn) 方法对核心塌缩超新星的弹跳后阶段进行轴对称 (2D) 多角度、多群中微子辐射流体动力学计算。我们跟踪了一个非旋转和一个快速旋转的 20 M☉ 恒星模型的核心在反弹后 160 到约 550 毫秒之间约 400 毫秒的长期弹跳后演化。我们对多角度中微子辐射场进行了多维分析，并与中微子输运的二维多群通量有限扩散（MGFLD）近似中进行的对应模拟进行了详细比较。我们发现，2D 多角度传输在捕获与旋转引起和 SASI 引起的非球面流体动力学配置相关的全局和局部辐射场变化方面具有优越性。在旋转模型中，多角度输运预测了更大的渐近中微子通量不对称性，极赤道比高达~2.5，而 MGFD 倾向于将光学半透明的震后区域中的辐射场球化。沿着两极，多角度计算预测中微子加热会急剧增强高达 3 倍，这会改变弹跳后的演化，导致极地激波半径更大，并且最初旋转减弱的 SASI 会更早出现。在非旋转模型中，当震后区域没有明显偏离球对称时，多角度和 MGFD 计算之间的差异在早期仍然很小。然而，后来，不断增长的 SASI 导致大规模的不对称，多角度计算预测平均积分中微子能量沉积率比 MGFLD 高出 30%。
We perform axisymmetric (2D) multiangle, multigroup neutrino radiation-hydrodynamic calculations of the postbounce phase of core-collapse supernovae using a genuinely 2D discrete-ordinate (Sn) method. We follow the long-term postbounce evolution of the cores of one nonrotating and one rapidly rotating 20 M☉ stellar model for ~400 milliseconds from 160 to ~550 ms after bounce. We present a multidimensional analysis of the multiangle neutrino radiation fields and compare in detail with counterpart simulations carried out in the 2D multigroup flux-limited diffusion (MGFLD) approximation to neutrino transport. We find that 2D multiangle transport is superior in capturing the global and local radiation-field variations associated with rotation-induced and SASI-induced aspherical hydrodynamic configurations. In the rotating model, multiangle transport predicts much larger asymptotic neutrino flux asymmetries with pole-to-equator ratios of up to ~2.5, while MGFLD tends to sphericize the radiation fields already in the optically semitransparent postshock regions. Along the poles, the multiangle calculation predicts a dramatic enhancement of the neutrino heating by up to a factor of 3, which alters the postbounce evolution and results in greater polar shock radii and an earlier onset of the initially rotationally weakened SASI. In the nonrotating model, differences between multiangle and MGFLD calculations remain small at early times when the postshock region does not depart significantly from spherical symmetry. At later times, however, the growing SASI leads to large-scale asymmetries and the multiangle calculation predicts up to 30% higher average integral neutrino energy deposition rates than MGFLD.