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- ID:
- ivo://CDS.VizieR/J/A+A/627/A51
- Title:
- Levels and rate coefficients of the Fe-L
- Short Name:
- J/A+A/627/A51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A major challenge in X-ray spectral modeling is the Fe-L spectrum, which is basically a complex assembly of n>=3 to n=2 transitions of Fe ions in different ionization states, affected by a range of atomic processes such as collisional excitation, resonant excitation, radiative recombination, dielectronic recombination, and innershell ionization. In this paper we perform a large-scale theoretical calculation on each of the processes with the flexible atomic code (FAC), focusing on ions of FeXVII to FeXXIV that form the main body of the Fe-L complex. The calculation includes a large set of energy levels with a broad range of quantum number n and l, taking into account the full-order configuration interaction and all possible resonant channels between two neighboring ions. The new data are found to agree within 20% with the recent individual R-matrix calculations for the main FeL lines, although the discrepancies become significantly larger for the weaker transitions, in particular for FeXVIII, FeXIX, and FeXX. By further testing the new FAC calculations with the high-quality RGS data from 15 elliptical galaxies and galaxy clusters, we note that the new model gives systematically better fits than the current SPEX v3.04 code, and the mean Fe abundance decreases by 12%, while the O/Fe ratio increases by 16% compared with the results from the current code. Comparing the FAC fit results to those with the $R$-matrix calculations, we find a temperature-dependent discrepancy of up to 10% on the Fe abundance between the two theoretical models. Further dedicated tests with both observed spectra and targeted laboratory measurements are needed to resolve the discrepancies, and ultimately to get the atomic data ready for the next high-resolution X-ray spectroscopy mission.
- ID:
- ivo://CDS.VizieR/J/A+A/654/A172
- Title:
- Photoionization of the CH radical
- Short Name:
- J/A+A/654/A172
- Date:
- 07 Mar 2022 07:12:57
- Publisher:
- CDS
- Description:
- The primary motivation of this paper is to provide accurate data for the photoionization of the CH radical, including absolute total photoionization cross section, partial cross sections and photo electron angular distribution. In addition,the near threshold features in the photoionization curve (which are absent in previous studies) are produced with high precision. A multichannel wavefunction based on R-matrix approach, which uses the configuration interaction (CI) method to describe electronic correlation, is carried out in the present calculations. A set of B-spline orbitals is employed to represent the accurate continuum. The distinctive feature of the present calculations allows us to generate a more accurate description of the bound and continuum states than those employed before. Total photoionization cross sections from the ground state of CH radicals and partial cross sections corresponding to 1{pi}, 3{sigma}, and 2{sigma} states of CH+ ions are presented for photon energies ranging from threshold to 80eV. Extensive resonance structures, which are absent in previous studies, near the ionization threshold, are observed for the first time. The cross-section dataset obtained from the present calculations is expected to be sufficiently accurate and comprehensive for most current modeling applications involving the photon and CH radicals scattering system.
- ID:
- ivo://CDS.VizieR/VI/56
- Title:
- Tests of shock chemistry in IC 443G
- Short Name:
- VI/56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The present study improves the computations of the collisional excitation rates by Green & Chapman (1978) for CS-H2; and by Bieniek & Green (1981) for SiO-H2. Part of the results are presented in the Appendix of the publication.
