Search

Time-dependent numerical simulations of the Kα complex of Fe xxvare carried out as a function of temperature–density–radiation field variations in high-temperature astrophysical and laboratory plasmas. In addition to several well-known features, the transient and steady-state spectra reveal the effects due to (a) time-dependent thermal and non-thermal radiation fields, (b) photo- and collisional excitation and ionization, and (c) high densities, on the‘quartet’ of principallines, and dielectronic satellites. The highly detailed models show precisely how, assuming a temporal–temperature correlation, the X-ray intensity varies between 6.6 and 6.7 keV and undergoes a‘spectral inversion’ in thewandzline intensities, characterizing an ionization- or a recombination-dominated plasma. The dielectronic satellite intensities are the most temperature-dependent features, but insensitive to density variations, and significantly contribute to the Kα complex forleading to asymmetric profiles. The 6.7-keV Kα complex should be a potential diagnostic of X-ray flares in active galactic nuclei, afterglows in gamma-ray bursts, and other non-equilibrium sources with the high-resolution measurements possible from the upcoming missionAstro-E2. It is also shown that high electron densities attenuate the line intensities in simulations relevant to laboratory plasmas, such as in inertial confinement fusion, laser, or magnetic Z-pinch devices. [ABSTRACT FROM AUTHOR]

ABSTRACT The Kα resonance complexes in oxygen ions O i–O viare theoretically computed, and resonance oscillator strengths and wavelengths are presented. The highly resolved photoionization cross-sections, with relativistic fine structure, are computed in the coupled channel approximation using the Breit–Pauli R-matrix method. A number of strong Kα resonances are found to be appreciable, with resonance oscillator strengths f[sub r] > 0.1 . The Kα resonance wavelengths of O i–O vilie in the relatively narrow wavelength range 22–23.5 Å, and the X-ray opacity in this region should therefore be significantly affected by K → L transitions in oxygen. The results should be useful in the interpretation of soft X-ray spectra observed from Chandra and XMM–Newton. [ABSTRACT FROM AUTHOR]

Asserts the domination of dielectronic satellites (DES) to the X-ray spectral formation in the 607-keV Kα complex of Fexxv. Definitions of diagnostic line ratio, DES and the lines with parameters from new relativistic atomic calculations; Source of the DES absorption resonance strengths from differential oscillator strengths; Assertion of the DES contribution to highly ionized iron.