Open AccessThe 6.7‐keV Kα complex of He‐like iron in transient plasmas ★
Author(s) -
Oelgoetz Justin,
Pradhan Anil K.
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.08269.x
Subject(s) - physics , plasma , atomic physics , ionization , spectral line , electron temperature , electron , electron density , magnetic field , collisional excitation , astrophysics , ion , nuclear physics , quantum mechanics , astronomy
Time‐dependent numerical simulations of the Kα complex of Fe xxv are 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 principal w , x , y , z lines, 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 the w and z line 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 for T < 6.7 keV leading 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 mission Astro‐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.