Parameterization of the level-resolved radiative recombination rate coefficients for the SPEX code

Junjie Mao, Jelle Kaastra

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The level-resolved radiative recombination (RR) rate coefficients for H-like to Na-like ions from H (Z = 1) up to and including Zn (Z = 30) are studied here. For H-like ions, the quantum-mechanical exact photoionization cross sections for nonrelativistic hydrogenic systems are used to calculate the RR rate coefficients under the principle of detailed balance, while for He-like to Na-like ions, the archival data on ADAS are adopted. Parameterizations are made for the direct capture rates in a wide temperature range. The fitting accuracies are better than 5% for about 99% of the 30, 000 levels considered here. The 1% exceptions include levels from low- charged many-electron ions, and/or high-shell (n>=4) levels are less important in terms of interpreting X-ray emitting astrophysical plasmas. The RR data will be incorporated into the high-resolution spectral analysis package SPEX.
Original languageEnglish
Article numberA84
Number of pages4
JournalAstronomy and Astrophysics
Early online date23 Feb 2016
Publication statusPublished - 31 Mar 2016


  • atomic data
  • atomic processes
  • high-resolution spectral analysis

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