We examine nucleosynthesis in the ejecta of black-hole–neutron-star mergers based on the results of long-term neutrino-radiation-magnetohydrodynamics simulations for the first time. We find that the combination of dynamical and postmerger ejecta reproduces a solarlike r-process pattern. Moreover, the enhancement level of actinides is highly sensitive to the distribution of both the electron fraction and the velocity of the dynamical ejecta. Our result implies that the mean electron fraction of dynamical ejecta should be ≳0.05 in order to reconcile the nucleosynthetic abundances with those in r-process-enhanced, actinide-boost stars. Since the tidal ejecta preserve the neutron richness in the inner crust of premerging neutron stars, this result provides an important constraint for nuclear equations of state if black-hole–neutron-star mergers are responsible for actinide-boost stars. Published by the American Physical Society 2024

中文翻译：

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黑洞-中子-星合并喷射物中的锕系元素助推 r 过程


我们首次根据长期中微子-辐射-磁流体动力学模拟的结果研究了黑洞-中子-星合并喷出物中的核合成。我们发现动态和合并后喷射物的组合再现了类似太阳的 r 过程模式。此外，锕系元素的增强水平对电子分数的分布和动态喷射物的速度都高度敏感。我们的结果表明，动力喷射物的平均电子分数应为 ≳0.05，以便将核合成丰度与 r 过程增强的锕系元素增强恒星中的原子合成丰度相协调。由于潮汐喷射物保留了前新兴中子星内壳中的中子丰富性，因此如果黑洞-中子星-中子星合并是锕系元素-助推星的原因，那么这一结果为核状态方程提供了重要约束。 美国物理学会 2024 年出版