Year: 2026
Type: article
Abstract: ABSTRACT Neodymium (Nd), a key r-process element, significantly influences the opacity and emergent spectra of kilonovae resulting from neutron star mergers. We present new atomic data for the first five ionization stages of Nd, with emphasis on recombination rate coefficients and electron-impact excitation relevant to non-local thermodynamic equilibrium (non-LTE) modelling. Using the relativistic atomic structure code autostructure, we compute energy levels, radiative recombination (RR) and dielectronic recombination (DR) rates using the isolated-resonance approximation, and excitation data for these ions. Excitation data sets are constructed using both direct (distorted wave) and resonant excitation approaches, allowing a systematic assessment of the impact of resonance contributions on effective collision strengths. For the case of Nd ii, we compare collisional strengths with those produced by the darc (Dirac Atomic R-matrix Codes). These comparisons demonstrate the importance of resonance-mediated excitation, especially for low-charge ions where near-threshold resonances significantly enhance rates. In terms of recombination for higher ionization stages, DR is found to dominate over a wide temperature range, while RR is comparable with DR at low temperatures for near-neutral species. Our results highlight the pivotal role of non-LTE atomic physics in interpreting kilonovae observations and constraining nucleosynthesis yields. This work strengthens the atomic foundation necessary for linking observed electromagnetic signals to the physics of compact object mergers and heavy element formation.
Institutions: University of Strathclyde, Queen's University Belfast
Language: English
Topic: Atomic and Molecular Physics
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,046
Funders: U.S. Department of Energy, Department for Business, Energy and Industrial Strategy, UK Government, UK Research and Innovation, National Energy Research Scientific Computing Center, University of Leicester, European Commission, University of Edinburgh, Office of Science, Science and Technology Facilities Council, H2020 European Research Council
OpenAlex ID: W7203768929
FWCI:
Cites:
Cited by:
Related to: