Nucleosynthesis studies of the origins of heavy nuclei using diverse observables and modern computational methods

使用不同的可观测值和现代计算方法对重核起源进行核合成研究

• 批准号: SAPIN-2022-00022
• 负责人: Vassh, Nicole
• 金额: $ 2.55万
• 依托单位: TRIUMF
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=765953
• 关键词: Nucleosynthesis; studies; origins; heavy; nuclei

Clues to the astrophysical origins of the heaviest elements observed in nature can be identified in a multitude of observables. For instance, our Sun reveals that the conditions in which it was born contained traces of elements synthesized by the slow (s) and rapid (r) neutron capture processes, which are responsible for the heaviest elements observed in nature. These processes have fingerprints in the form of distinct "peaks" seen in solar and stellar elemental abundances. Computational methods provide a modern way to go backwards from observables to fundamental physics. The proposed work will train a machine learning algorithm to recognize r-process and s-process patterns. Then when confronted with stellar patterns, it can provide an estimate of the contributions of each process. Previously we applied statistical methods to find the nuclear mass required to form the solar r-process rare-earth peak (containing elements such as europium) which is presently of uncertain origin. Comparisons between our predicted masses and those measured in laboratories provided insights on the astrophysical production of rare-earth elements. Proposed work will expand upon this by considering alternative statistical methods and by targeting masses of nuclei known to be responsible for other solar abundance peaks. Access to additional observables has grown in recent years, evidenced by multi-messenger detections such as the first ever observed binary neutron star merger (NSM) GW170817, from which both the gravitational wave and light was detected. The light from this event provided the first direct evidence that NSMs synthesize at least some r-process elements. However, whether NSM events produce the heaviest species such as gold and uranium, and whether mergers explain the heavy element content of our Solar System, remains unclear. Proposed work will build on previous studies which compared the NSM frequency inferred from GW170817 to the predicted frequency needed to explain europium in the Solar System by examining other elements and incorporating future detections. Proposed work will also build a catalog of light curve predictions when specific isotopes are produced to help identify the presence of species in future NSMs. Since our ability to interpret observables is critically influenced by the nuclear properties of species both within and beyond experimental reach, these studies will serve to guide future theoretical and experimental research programs. Hydrodynamic simulations are refining our understanding of explosive events such NSMs and exotic magneto-rotationally driven supernovae (MHDs) which could host an r process. Since neutrino interactions critically influence the predicted nucleosynthesis, proposed work will include a first treatment of the magnetic interaction of neutrinos in MHDs. The proposed studies will therefore synergize simultaneous progress across disciplines to address the fundamental open science question of our own cosmic origins.

在自然界中观测到的最重元素的天体物理学起源的线索可以在众多的观测数据中找到。例如，我们的太阳揭示了它诞生的条件包含由慢（s）和快（r）中子捕获过程合成的元素的痕迹，这是自然界中观察到的最重元素的原因。这些过程有指纹的形式，在太阳和恒星元素丰度的明显的“峰”。计算方法提供了一种从可观测到基础物理的现代方法。所提出的工作将训练机器学习算法来识别r-过程和s-过程模式。然后，当面对恒星模式时，它可以提供每个过程的贡献的估计。以前，我们应用统计方法来寻找形成太阳r-过程稀土峰（含有铕等元素）所需的核质量，目前尚不确定其来源。我们预测的质量和实验室测量的质量之间的比较提供了对稀土元素天体物理生产的见解。拟议的工作将通过考虑替代的统计方法和针对已知负责其他太阳丰度峰值的原子核质量来扩展这一点。近年来，对更多可观测量的获取有所增加，多信使探测证明了这一点，例如第一个观测到的双星中子星星合并（NSM）GW 170817，从那里探测到了引力波和光。来自这一事件的光提供了第一个直接证据，证明NSM至少合成了一些r-过程元素。然而，NSM事件是否产生了最重的物质，如金和铀，以及合并是否解释了我们太阳系的重元素含量，仍然不清楚。拟议的工作将建立在以前的研究基础上，这些研究将从GW 170817推断的NSM频率与通过检查其他元素并结合未来的检测来解释太阳系中铕所需的预测频率进行了比较。拟议的工作还将建立一个目录的光变曲线预测时，特定的同位素产生，以帮助确定物种的存在，在未来的NSM。由于我们解释观测量的能力受到实验范围内和实验范围外物种核特性的严重影响，这些研究将指导未来的理论和实验研究计划。流体动力学模拟正在完善我们对爆炸事件的理解，如NSM和外来的磁旋转驱动的超新星（MHD），它们可能会发生r过程。由于中微子的相互作用严重影响预测的核合成，拟议的工作将包括第一次治疗的中微子磁相互作用的MHD。因此，拟议的研究将协同跨学科的同步进展，以解决我们自己的宇宙起源的基本开放科学问题。