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Atomic structure calculations in lanthanide ions relevant to kilonovae
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Orientador(es)
Resumo(s)
The present dissertation concerns atomic structure calculations for lanthanide and actinide ions that are significant to kilonovae modeling of the ejecta spectra. In particular, calculations for Nd III and U III, two representative rare-earth ions, were achieved. Therefore, in this work we try to bridge the gap created by the lack of atomic structure calculations f-block ions available in the literature, while also providing valuable insight for future calculations. We concentrated on level energies and oscillator strength calculations for electric dipole transitions (E1) since these are the most critical atomic parameters for simulating the flux of kilonovae in Local Thermodinamical Equilibrium (LTE). We mainly use the publicly accessible Flexible Atomic Code (FAC) for the computations, which employs a Relativistic Configuration Interaction (RCI) method. Not only that, but we compare our results to those obtained using a Multi-configuration Dirac-Fock (MCDF) method as well as to available computational and experimental data. We demonstrated that discrepancies in the opacity spectra of Nd III across various calculations are higher at the ultraviolet and visible wavelengths. At longer wavelengths the sensitivity of the opacity with the accuracy of the calculations seems to decrease. Additionally, we showed the opacity of U III to be about an order of magnitude higher than the opacity of Nd III due to a higher density of levels of the actinide. In general, we anticipate this feature of the spectrum to extend for more lanthanide-actinide pairs and, therefore, that the opacity of actinides to have a measurable impact in the luminosity of kilonovae.
Descrição
Tese de mestrado, Física (Física Nuclear e Partículas) Universidade de Lisboa, Faculdade de Ciências, 2021
Palavras-chave
opacidade dados atómicos kilonovas forças de oscilador estrelas de neutrões Teses de mestrado - 2021