K-shell photoabsorption and photoionization of trace elements. II. Isoelectronic sequences with electron number $12\le N\le 18$

Abstract

We are concerned with improving the diagnostic potential of the K lines and edges of elements with low cosmic abundances that are observed in the X-ray spectra of supernova remnants, galaxy clusters and accreting black holes and neutron stars. Since accurate photoabsorption and photoionization cross sections are needed in their spectral models, they have been computed for isoelectronic sequences with electron number $12\le N\le 18$ using a multi-channel method. Target representations are obtained with the atomic structure code AUTOSTRUCTURE, and ground-state cross sections are computed with the Breit--Pauli $R$-matrix method (BPRM) in intermediate coupling, including damping (radiative and Auger) effects. The contributions from channels associated with the 2s-hole $[2\mathrm{s}]\mu$ target configurations and those containing 3d orbitals are studied in the Mg and Ar isoelectronic sequences. Cross sections for the latter ions are also calculated in the isolated-resonance approximation as implemented in AUTOSTRUCTURE and compared with BPRM to test their accuracy. It is confirmed that the collisional channels associated with the $[2\mathrm{s}]\mu$ target configurations must be taken into account owing to significant increases in the monotonic background cross section between the L and K edges. Target configurations with 3d orbitals give rise to fairly conspicuous unresolved transition arrays in the L-edge region, but to a much lesser extent in the K-edge which is our main concern; therefore, they have been neglected throughout owing to their computationally intractable channel inventory, thus allowing the computation of cross sections for all the ions with $12\le N\le 18$ in intermediate coupling with BPRM. We find that the isolated-resonance approximations performs satisfactorily.

arXiv commentAccepted for publication in Astronomy & Astrophysics. 5 pages, 6 figures

References in corpus (21)

• The magnetic nature of disk accretion onto black holes
• GRS 1915+105 in "Soft State": Nature of Accretion Disk Wind and Origin of X-Ray Emission
• Spectrum Synthesis Modeling of the X-ray Spectrum of GRO J1655-40 Taken During the 2005 Outburst
• The X-ray Line Emission from the Supernova Remnant W49B
• K-shell Photoabsorption of Oxygen Ions
• The Persistence of Memory, or How the X-Ray Spectrum of SNR 0509-67.5 Reveals the Brightness of its Parent Type Ia Supernova
• X-ray Spectroscopy of the Core of the Perseus Cluster with Suzaku: Elemental Abundances in the Intracluster Medium
• K-Shell Photoionization of Singly Ionized Atomic Nitrogen: Experiment and Theory
• Nitrogen K-shell photoabsorption
• Discovery of K-Shell Emission Lines of Neutral Atoms in the Galactic Center Region
• Photoionization modeling of oxygen K absorption in the interstellar medium:the Chandra grating spectra of XTE J1817-330
• A Super-Solar Metallicity for the Progenitor of Kepler's Supernova
• On the Structure of the Iron K-Edge
• A Comprehensive X-ray Absorption Model for Atomic Oxygen
• High Precision {\it K}-Shell Photoabsorption Cross Sections for Atomic Oxygen: Experiment and Theory
• K-shell photoionization of Na-like to Cl-like ions of Mg, Si, S, Ar, and Ca
• Physical properties of the interstellar medium using high-resolution Chandra spectra: O K-edge absorption
• Radiative and Auger decay data for modelling nickel K lines
• Modeling the oxygen K absorption in the interstellar medium: an {\it XMM}-Newton view of Sco X-1
• K-Shell Photoionization of B-like Oxygen (O${}^{3+}$) Ions: Experiment and Theory
• K-shell photoionization of Nickel ions using R-matrix

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