Dielectronic Recombination of Argon-Like Ions

TL;DR

This paper provides new theoretical calculations of dielectronic recombination rates for Ar-like ions, improving the accuracy of ionization models relevant to astrophysical plasmas and X-ray absorption features.

Contribution

It introduces detailed DR rate coefficients for a range of Ar-like ions using advanced computational methods, addressing gaps and uncertainties in previous empirical data.

Findings

New DR rate coefficients for K II -- Zn XIII ions.

Questioning the reliability of existing empirical rate formulas.

Enhanced modeling accuracy for astrophysical plasma ionization balance.

Abstract

We present a theoretical investigation of dielectronic recombination (DR) of Ar-like ions that sheds new light on the behavior of the rate coefficient at low-temperatures where these ions form in photoionized plasmas. We provide results for the total and partial Maxwellian-averaged DR rate coefficients from the initial ground level of K II -- Zn XIII ions. It is expected that these new results will advance the accuracy of the ionization balance for Ar-like M-shell ions and pave the way towards a detailed modeling of astrophysically relevant X-ray absorption features. We utilize the AUTOSTRUCTURE computer code to obtain the accurate core-excitation thresholds in target ions and carry out multiconfiguration Breit-Pauli (MCBP) calculations of the DR cross section in the independent-processes, isolated-resonance, distorted-wave (IPIRDW) approximation. Our results mediate the complete absence of direct DR calculations for certain Ar-like ions and question the reliability of the existing empirical rate formulas, often inferred from renormalized data within this isoelectronic sequence.