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

关于自然界中观察到的最重元素的天体物理起源的线索，可以在大量的观测资料中找到。例如，我们的太阳揭示了它出生的条件下含有由慢(S)和快(R)中子俘获过程合成的元素的痕迹，这是自然界中观察到的最重的元素。这些过程的指纹在太阳和恒星元素丰度中可以看到不同的“峰”。计算方法提供了一种从可观测到基础物理倒退的现代方法。这项拟议的工作将训练一种机器学习算法来识别r-过程和S-过程模式。然后，当遇到恒星模式时，它可以提供每个过程的贡献估计。在此之前，我们应用统计方法找到了形成太阳r-过程稀土峰(包含Eu等元素)所需的核质量，目前还不确定其来源。我们预测的质量与实验室测量的质量之间的比较，为稀土元素的天体物理生产提供了见解。拟议的工作将通过考虑替代统计方法和针对已知对其他太阳丰度峰值负责的大量原子核来扩展这一点。近年来，对更多可观测到的天体的访问有所增加，多信使探测证明了这一点，例如首次观测到的双中子星合并(NSM)GW170817，从中既探测到引力波，又探测到光。来自这一事件的光提供了第一个直接证据，证明NSM合成了至少一些r-过程元素。然而，NSM事件是否产生了金和铀等最重的物种，以及合并是否解释了我们太阳系中的重元素含量，目前尚不清楚。拟议的工作将建立在以前研究的基础上，这些研究将从GW170817推断的NSM频率与通过检查其他元素并结合未来探测来解释太阳系中Eu所需的预测频率进行比较。拟议的工作还将建立一个特定同位素产生时的光曲线预测目录，以帮助识别未来NSM中物种的存在。由于我们解释可观测的能力受到实验范围内和实验范围外物种核属性的严重影响，这些研究将有助于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和可能存在r过程的奇异磁旋驱动超新星(MHD)。由于中微子相互作用对预测的核合成有至关重要的影响，建议的工作将包括对MHD中微子磁相互作用的第一次处理。因此，拟议的研究将协同各学科的同步进展，以解决我们自己宇宙起源的基本开放科学问题。

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.