发表机构
Physics of the Universe Program, Zewail City of Science and Technology; Department of Physics, Faculty of Science, Cairo University（泽维尔科学与技术城宇宙物理项目; 开罗大学理学院物理系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究利用$^{225}\text{Ra}$-$^{225}\text{Ac}$衰变序列建立了同位素份额与衰变时间的关联条件，揭示了其产生记忆对并合晚期辐射的影响，为核合成及辐射输运计算提供了基准。
AI 中文摘要
中子星并合抛射物中的放射性原子核携带了其丰度和产生历史的信息。利用$^{225}\text{Ra}$-$^{225}\text{Ac}$衰变序列，我们建立了存活同位素份额与母核衰变可用时间之间的精确关联条件：仅通过Ra衰变产生的Ac占比为0.1时，所需时间至少为2.456天，这为所提出的源状态提供了直接的一致性检验。我们表明，后续的放射性活度保留了额外的产生记忆：两个具有相同平均诞生时间的产生历史可产生不同的响应交点，这种差异可通过解析方法捕捉，将平均时间顺序与产生时间分布的影响区分开。受控辐射计算进一步显示，对于固定的抛射物性质，沉积与光子逃逸如何将核对比度转化为共同的光变曲线枢轴点。这些结果将核产生年代学与并合晚期辐射联系起来，为核合成及辐射输运计算提供了基准。
英文摘要
Radioactive nuclei in neutron-star merger ejecta carry information about both their abundance and their production history. Using the $^{225}\mathrm{Ra}$-$^{225}\mathrm{Ac}$ sequence, we establish exact conditions linking a surviving isotope partition to the time available for parent decay. An Ac fraction of 0.1 produced solely through Ra decay requires at least 2.456 days, providing a direct consistency test for proposed source states. We show that subsequent activity retains additional production memory: two histories with the same mean birth time can produce different response crossings. This distinction is captured analytically and separates mean chronology from the influence of the production-time distribution. A controlled radiation calculation then shows how deposition and photon escape transform the nuclear contrast into a common light-curve pivot for fixed ejecta properties. The results connect nuclear production chronology to late-time merger emission and provide benchmarks for nucleosynthesis and radiation-transport calculations.
Comments6 pages, 3 Figures
