Journal ArticleDOI
Indirect X-Ray Line-Formation Processes in Iron L-Shell Ions
TLDR
In this paper, the role of indirect processes in the soft X-ray line formation of iron L-shell ions, using a newly developed, relativistic, multiconfigurational atomic package, was investigated.Abstract:
We present a systematic study of the role of indirect processes in the soft X-ray line formation of iron L-shell ions, using a newly developed, relativistic, multiconfigurational atomic package. These indirect processes involve the neighboring charge states of the target ion, namely, radiative recombination, dielectronic recombination, and resonance excitation. For Fe XVII, the inner-shell collisional ionization (CI) is also relevant. Lines originating from 3s and 3p upper levels of Fe XVII-XX are found to be significantly affected by these processes, with some lines being enhanced by nearly a factor of 2 at the temperature of maximum fractional abundance in CI equilibrium. Such enhancement, although not enough to completely explain the observed line ratios from various astrophysical sources, is a vast improvement over the previous models neglecting these processes. Rate coefficients for individual processes are tabulated, which can be conveniently included in spectral models to correctly account for these effects. As a by-product of this investigation, the total recombination and ionization rates of all Fe L-shell ions are tabulated as a function of temperature.read more
Citations
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The flexible atomic code
TL;DR: In this paper, a complete software package for the computation of various atomic data such as energy levels; radiative transition; collisional excitation; ionization by electron impact, photoionizatio...
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Chianti—an atomic database for emission lines. xiii. soft x-ray improvements and other changes
TL;DR: The CHIANTI spectral code as mentioned in this paper consists of two parts: an atomic database and a suite of computer programs in Python and IDL, together, they allow the calculation of the optically thin spectrum of astrophysical objects and provide spectroscopic plasma diagnostics for the analysis of the astrophysical spectra.
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X-ray Spectroscopy of Cooling Clusters
TL;DR: In this paper, the authors review the X-ray spectra of the cores of clusters of galaxies, and discuss several viable mechanisms designed to cancel or distort the expected process of cooling.
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CHIANTI - an atomic database for emission lines. IX. Ionization rates, recombination rates, ionization equilibria for the elements hydrogen through zinc and updated atomic data
TL;DR: The CHIANTI database as mentioned in this paper provides a set of atomic data for the interpretation of astrophysical spectra emitted by collisionally dominated, high temperature, optically thin sources.
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CHIANTI-An Atomic Database for Emission Lines. VII. New Data for X-Rays and Other Improvements
TL;DR: The CHIANTI atomic database as mentioned in this paper contains atomic energy levels, wavelengths, radiative transition probabilities, and collisional excitation data for a large number of ions of astrophysical interest.
References
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Journal ArticleDOI
Binary-encounter-dipole model for electron-impact ionization
Yong-Ki Kim,M. Eugene Rudd +1 more
TL;DR: In this article, a theoretical model for calculating electron-impact ionization cross sections for atoms and molecules is presented, which combines the binary-encounter theory with the dipole interaction of the Bethe theory for fast incident electrons.
Journal ArticleDOI
Iron ionization and recombination rates and ionization equilibrium
M. Arnaud,J. Raymond +1 more
TL;DR: In this article, a critical review of the existing data on ionization and dielectronic recombination and present new computations of radiative recombination rate coefficients of Fe(+14) through Fe(−25) using the photoionization cross sections of Clark et al.
Journal ArticleDOI
HULLAC, an integrated computer package for atomic processes in plasmas
TL;DR: H ULLAC as mentioned in this paper, an integrated code for calculating atomic structure and cross sections for collisional and radiative atomic processes, is based on relativistic quantum mechanical calculations including configuration interaction.
Journal ArticleDOI
High-Resolution X-Ray Spectra of Capella: Initial Results from the Chandra High-Energy Transmission Grating Spectrometer
Claude R. Canizares,David P. Huenemoerder,David S. Davis,Daniel Dewey,Kathryn A. Flanagan,John C. Houck,Thomas H. Markert,Herman L. Marshall,Mark L. Schattenburg,Norbert S. Schulz,Michael W. Wise,Jeremy J. Drake,Nancy Brickhouse +12 more
TL;DR: In this article, high-resolution spectra of the active binary Capella (G8 III + G1 III) covering the energy range of 0.4-8.0 keV (1.5-30 A) show a large number of emission lines, demonstrating the performance of the High Energy Transmission Grating Spectrometer.
Journal ArticleDOI
Laboratory Measurements and Modeling of the Fe XVII X-Ray Spectrum
Gregory V. Brown,Gregory V. Brown,Peter Beiersdorfer,Duane A. Liedahl,Klaus Widmann,Steven M. Kahn +5 more
TL;DR: In this article, the Fe XVII L-shell emission spectrum between 9.8 and 17.5 A was analyzed under precisely controlled conditions where electron-impact excitation followed by radiative cascades is the dominant line formation process.