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Theoretical Spectra of Lanthanides for Kilonovae Events: Ho I-III, Er I-IV, Tm I-V, Yb I-VI, Lu I-VII
Version 1
: Received: 22 November 2023 / Approved: 23 November 2023 / Online: 23 November 2023 (06:56:18 CET)
A peer-reviewed article of this Preprint also exists.
Nahar, S.N. Theoretical Spectra of Lanthanides for Kilonovae Events: Ho I-III, Er I-IV, Tm I-V, Yb I-VI, Lu I-VII. Atoms 2024, 12, 24. Nahar, S.N. Theoretical Spectra of Lanthanides for Kilonovae Events: Ho I-III, Er I-IV, Tm I-V, Yb I-VI, Lu I-VII. Atoms 2024, 12, 24.
Abstract
The broad emission bump in the electromagnetic spectra observed
following the detection of gravitational waves created during the
kilonova event of merger of two neutron stars in August 2017, GW170817,
has been linked to the heavy elements of lanthanides (Z=57-71), and a
new understanding of creation of heavy elements in the r-process. The
initial spectral emission bump has a wavelength range of 3000 - 7000
\AA, thus covering the region of ultraviolet (UV) to optical (O)
wavelengths, and is similar to those seen for lanthanides. Most
lanthanides have large number of
closely lying energy levels which introduce extensive sets of
radiative transitions which often form broad region of lines of significant
strength.
The current study explores these broad features through
photoabsorption spectroscopy of 25 lanthanides ions, Ho I-III, Er I-IV,
Tm I-V, Yb I-VI and Lu I-VII. With excitations only to a few orbitals
up beyond the ground configurations, we find most of these ions cover
large number of bound levels with open $4f$ orbital and produce
tens to about hundred thousands lines that may form one or multiple
broad features in X-ray to UV, O, and infrared (IR) regions. Spectrum
of each of 25 ions is presented indicating presence, shape and
wavelength region of the features. Accuracy of
atomic data to interpret the merger spectra has been a outstanding
problem. The present study aims at providing improved atomic data
for energies and transition parameters obtained using relativistic
Breit-Pauli approximation implemented in the atomic structure
code SUPERSTRUCTURE. The present data have been benchmarked with
available experimental data for energies and transition parameters.
The study finds that number of ions
under the present study are possible contributors of the emission
bump of GW170817. All atomic data will be made available online at
NORAD-Atomic-Data database.
Keywords
Atomic data; energies; transition parameters; photo-excitation cross sections; photoabsorption spectra; Lanthanide ions - Ho I-III, Er I-IV, Tm I-V, Yb I-VI, Lu I-VII; broad emission bumps
Subject
Physical Sciences, Atomic and Molecular Physics
Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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