热核超新星中电子俘获元素的产生：理论与观测
The Production of Electron-Capture Elements in Thermonuclear Supernovae: Theory vs. Observations
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中文总结 AI 辅助
本文通过磁流体力学模拟，结合JWST观测，发现预存湍流会减少电子俘获元素产生量，指出需重新聚焦相关超新星模型及低Ye下的高精度电子俘获反应率。
中文摘要 AI 辅助
Ia型超新星（SNe Ia）会在多个恒星系统中爆发性摧毁碳氧白矮星（WDs），它们产生了宇宙中约50%的铁族元素，合成电子俘获（EC）元素，推动核物理实验，并为高精度宇宙学提供基础。从一级近似来看，其结果由核物理决定，这一特性常被称为“恒星失忆”。近年来，JWST对EC元素的近乎普遍探测开始打破这种“恒星失忆”状态。这些元素是高密度燃烧的示踪物，在很大程度上排除了目前流行的氦触发亚钱德拉塞卡（sub-Mch）爆轰模型作为主导通道的可能性。相反，EC元素的普遍存在将研究重点重新转向动力学与长期合并，以及接近钱德拉塞卡质量（near-Mch）的爆炸，这类爆炸类似爆燃模型W7，但其中核火焰会经历爆燃到爆轰的转变。早期爆燃阶段尤为重要，因为球对称模拟将白矮星中心密度，进而白矮星质量，确定为控制爆炸的关键参数。本文中，我们给出了详细的磁流体力学模拟结果，发现爆炸前闷烧阶段预期存在的小尺度预存湍流，对于克服固有三维物理带来的基础挑战至关重要；这种湍流会系统性地使EC元素的产生量减少约一半，意味着需要更接近吸积诱导坍缩为中子星相关的白矮星中心密度。我们还展示了接近饱和场强的磁场的影响，并强调了在低电子丰度（Ye）下需要更高精度的EC反应率。
英文摘要
Type Ia supernovae (SNe Ia) explosively destroy carbon-oxygen white dwarfs (WDs) in multiple stellar systems. They produce approximately 50% of the iron-group elements in the Universe, synthesize electron-capture (EC) elements, drive nuclear physics experiments, and underpin high-precision cosmology. To first order, the outcome is governed by nuclear physics, a property often described as stellar amnesia. Recently, this stellar amnesia has begun to be broken by the nearly universal detection of EC elements with JWST. These elements trace high-density burning, largely ruling out the currently popular helium-triggered, sub-Mch detonation models as the dominant channel. Instead, the ubiquitous presence of EC is shifting back the focus to dynamical and secular mergers, and near-Mch explosions similar to the deflagration model W7, but in which the nuclear flame undergoes a deflagration-to-detonation transition. The early deflagration phase is especially important because spherical simulations identify the central WD density, and thus the WD mass, as a key parameter governing the explosion. Here, we present detailed magneto-hydrodynamical simulations. We find that small-scale, pre-existing turbulence expected from the pre-explosion smoldering phase is essential for overcoming the fundamental challenges imposed by the intrinsic 3D physics. This turbulence systematically reduces the production of EC elements by about a factor of two, implying the need for WD central densities closer to those associated with accretion-induced collapse to a neutron star. We also demonstrate the effect of magnetic fields near the saturation field strength and highlight the need for higher-precision EC rates at low Ye.
