Dielectronic recombination of argon-like ions

¹ Department of Physics, Western Michigan University, Kalamazoo, MI 49008, USA e-mail: gorczyca@wmich.edu
² Department of Physics, University of Strathclyde, Glasgow G4 0NG, UK

Received: 23 March 2010
Accepted: 16 April 2010

Abstract

Context. 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.

Aims. 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.

Methods. 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.

Results. 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.