AI 中文总结
本研究通过数值相对论模拟，探究旋转大质量恒星核心坍缩为黑洞的过程，明确核燃烧对坍缩模式、抛射物特征及铁族元素生成的影响，揭示其可产生大质量高能抛射物与铁族元素的机制。
AI 中文摘要
我们利用包含α链核反应网络和中微子冷却的数值相对论模拟，研究旋转大质量及超大质量恒星核心的坍缩过程。本次研究的主要对象是新构建的初始核心质量为$2×10^3-5×10^4M_⊙$的模型。坍缩的触发机制分为两类：质量较小的核心由对不稳定性触发，质量较大的核心则由广义相对论不稳定性触发。我们发现，质量较大的核心会经历近同源坍缩，而质量较小的核心则表现出更剧烈的类失控坍缩，原因在于其更高的密度和温度使中微子冷却效率显著提升。因此，质量较小模型中形成的黑洞最初包含的核心质量占比更小，且在黑洞外仍残留大量物质时就会形成吸积盘；对不稳定核心的较低致密性也使其能拥有更大的无量纲角动量，有利于快速旋转黑洞和大质量吸积盘的形成。吸积盘反弹驱动的物质抛射，其抛射物质量约为$10-10^3M_⊙$，动能约为$10^{53}-10^{55}\\,\mathrm{erg}$。仅在质量最小的模型中，吸积盘反弹抛射物会产生大量$^{56}$镍。针对部分模型，我们进一步追踪了吸积盘的粘滞演化，发现粘滞作用会提升抛射物质量和动能；在核心质量≤$10^4M_⊙$的模型中，粘滞驱动的抛射物可来自达到核统计平衡的吸积盘物质，因此富含$^{56}$镍。这些结果表明，旋转大质量恒星坍缩可产生大质量、高能量的抛射物，且在核心质量足够低时能生成大量铁族元素。
英文摘要
We investigate the collapse of rotating very massive and supermassive stellar cores using numerical relativity simulations including an alpha-chain nuclear reaction network and neutrino cooling. Our main survey focuses on newly constructed models with initial core masses of $2 \times {10}^{3}-5\times 10^4M_\odot$. The collapse is triggered either by pair instability in lower-mass cores or by general-relativistic instability in higher-mass cores. We find that higher-mass cores undergo a nearly homologous collapse, whereas lower-mass cores show a more runaway-like collapse because neutrino cooling becomes more efficient at their higher densities and temperatures. Consequently, the black hole formed in lower-mass models initially contains a smaller fraction of the core mass, and disk formation occurs while a larger amount of matter remains outside the black hole. The lower compactness of pair-unstable cores also allows larger dimensionless angular momentum, favoring the formation of rapidly rotating black holes and massive disks. The disk bounce drives mass ejection with ejecta masses of order $10-10^3M_\odot$ and kinetic energies of order $10^{53}-10^{55}\,\mathrm{erg}$. Significant $^{56}$Ni production in the disk-bounce ejecta occurs only in the lowest-mass models. For selected models, we further follow the viscous evolution of the disk and find that viscosity enhances the ejecta mass and kinetic energy. In models with $\lesssim10^4M_\odot$, the viscosity-driven ejecta can originate from disk matter that has reached nuclear statistical equilibrium and can therefore become rich in $^{56}$Ni. These results suggest that rotating very massive star collapses can produce massive, energetic ejecta and, for sufficiently low core masses, substantial iron-group elements.
Comments23 pages, 13 figures. Submitted to ApJ
