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

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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.