Theoretical study of Th III energy levels and transitions for applications to kilonova spectra

Fuente: arXiv
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Autori principali: Kitovienė, Laima, Gaigalas, Gediminas, Rynkun, Pavel, Domoto, Nanae, Tanaka, Masaomi, Kato, Daiji
Natura: Preprint
Pubblicazione: 2025
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author Kitovienė, Laima
Gaigalas, Gediminas
Rynkun, Pavel
Domoto, Nanae
Tanaka, Masaomi
Kato, Daiji
author_facet Kitovienė, Laima
Gaigalas, Gediminas
Rynkun, Pavel
Domoto, Nanae
Tanaka, Masaomi
Kato, Daiji
contents The neutron star merger is a promising site of heavy element production. By producing heavy elements, the neutron star merger gives rise to a thermal transient called a kilonova. Studying kilonova spectra enables us to quantify the heavy element production. Among the heaviest elements, doubly ionized Thorium (Th, Z=90) is one of the important candidates for producing detectable absorption features in kilonova spectra. This paper investigates the atomic properties of Th III to provide energy level and transition data. The multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction methods, which are implemented in the general-purpose relativistic atomic structure package GRASP2018, are used to compute energy levels of the $\mathrm{5f6d}$, $\mathrm{6d^2}$, $\mathrm{7s^2}$, $5\mathrm{f^2}$, $\mathrm{6d7s}$, $\mathrm{5f7p}$ and $\mathrm{5f7s}$ configurations and electric dipole transitions between states of these configurations. The accuracy of energy levels is evaluated by comparing it with experimental data and with various theoretical methods. Our calculated energy levels are consistent with the experimental results with a root mean square (RMS) deviation of 436 cm$^{-1}$. The accuracy of transition data is investigated using the quantitative and qualitative evaluation method.By performing radiative transfer simulations for kilonova spectra with our transition data, we show that kilonova including Th with a mass fraction of $(3-10) \times 10^{-5}$ can produce Th III absorption features around 18,000 A.
format Preprint
id arxiv_https___arxiv_org_abs_2502_20424
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Theoretical study of Th III energy levels and transitions for applications to kilonova spectra
Kitovienė, Laima
Gaigalas, Gediminas
Rynkun, Pavel
Domoto, Nanae
Tanaka, Masaomi
Kato, Daiji
High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
The neutron star merger is a promising site of heavy element production. By producing heavy elements, the neutron star merger gives rise to a thermal transient called a kilonova. Studying kilonova spectra enables us to quantify the heavy element production. Among the heaviest elements, doubly ionized Thorium (Th, Z=90) is one of the important candidates for producing detectable absorption features in kilonova spectra. This paper investigates the atomic properties of Th III to provide energy level and transition data. The multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction methods, which are implemented in the general-purpose relativistic atomic structure package GRASP2018, are used to compute energy levels of the $\mathrm{5f6d}$, $\mathrm{6d^2}$, $\mathrm{7s^2}$, $5\mathrm{f^2}$, $\mathrm{6d7s}$, $\mathrm{5f7p}$ and $\mathrm{5f7s}$ configurations and electric dipole transitions between states of these configurations. The accuracy of energy levels is evaluated by comparing it with experimental data and with various theoretical methods. Our calculated energy levels are consistent with the experimental results with a root mean square (RMS) deviation of 436 cm$^{-1}$. The accuracy of transition data is investigated using the quantitative and qualitative evaluation method.By performing radiative transfer simulations for kilonova spectra with our transition data, we show that kilonova including Th with a mass fraction of $(3-10) \times 10^{-5}$ can produce Th III absorption features around 18,000 A.
title Theoretical study of Th III energy levels and transitions for applications to kilonova spectra
topic High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2502.20424