Collaborative Research: Bound-Bound and Bound-Free Opacities of Heavy Lowly-Charged r-Process Ions

这个研究项目是美国东南部三所主要大学的合作成果。研究小组将对中子星合并过程中产生的重元素进行理论和实验研究，这些重元素最近被证明是引力波的来源。研究人员将计算这些元素的光学和红外特征，并在实验室中进行高精度测量。关于这些元素的数据非常有限，以至于很难解释中子星合并的观测结果。这项研究的结果将使天文学家能够准确地解释中子星合并的光谱观察结果，并了解重元素是如何在这种合并中形成的。该项目将为学生提供研究培训，以及在这三所院校从事不同但相关主题的工作的机会。研究小组将研究所谓的“第二峰”元素——Re、Os、Ir、Au和Pt——因为据预测，这些元素在中子星合并中形成的丰度相对较高。他们将首先使用高度精确和复杂的量子方法计算这些元素的原子能级和跃迁概率。然后，他们将测量元素的光学和红外光谱，以对计算进行基准测试。结果将得到可靠的性质和准确的谱线表，可用于中子星合并光谱中这些元素的识别和它们的丰度测定。这也将有助于阐明在太空中合成重元素的快中子捕获过程——或称“r过程”。本项目将培养理论和实验原子物理学以及天体物理学的研究生和本科生。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This research project is a collaborative effort between three major universities in the southeastern United States. The research team will undertake a combined theoretical and experimental study of heavy elements that are produced in neutron star mergers, which have recently been shown to be gravitational wave sources. The researchers will calculate the optical and infrared signatures of these elements and measure them in the laboratory to high accuracy. Data on these elements are so limited that it is difficult to interpret observations of neutron star mergers. Results from the study will allow astronomers to accurately interpret spectroscopic observations of neutron star mergers and to understand how heavy elements are formed in such mergers. The project will provide students with research training, as well as opportunities to work on diverse but related topics at the three institutions.The research team will study the so-called "second peak" elements --- Re, Os, Ir, Au, and Pt --- because these are predicted to be formed at relatively high abundances in neutron star mergers. They will first calculate the atomic energy levels and transition probabilities of these elements using highly accurate and sophisticated quantum methods. They will then measure the optical and infrared spectra of the elements to benchmark the calculations. The result will be reliable properties and accurate spectral line lists, which can be used for the identification of these elements and determination of their abundances in the spectra of neutron star mergers. This will also help shed light on the rapid neutron capture process --- or "r-process" --- involved in the synthesis of heavy elements in space. This project will train graduate and undergraduate students in theoretical and experimental atomic physics, as well as astrophysics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.