Photoionization Modeling and the K Lines of Iron

By T. Kallman, P. Palmeri, M. Bautista, C. Mendoza, J. H. K. L. F. H. E. Astrophysics, Nasagsfc, Greenbelt, MD Department of Astronomy, U. Maryland, College Park and 7 more. 2004

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We calculate the efficiency of iron K line emission and iron K absorption in photoionized models using a new set of atomic data. These data are more comprehensive than those previously applied to the modeling of iron K lines from photoionized gases and allow us to systematically examine the behavior of the properties of line emission and absorption as a function of the ionization parameter, density, and column density of model constant density clouds. We show that, for example, the net fluorescence yield for the highly charged ions is sensitive to the level population distribution produced by photoionization, and these yields are generally smaller than those predicted assuming the population is according to statistical weight. We demonstrate that the effects of the many strongly damped resonances below the K ionization thresholds conspire to smear the edge, thereby potentially affecting the astrophysical interpretation of absorption features in the 7-9 keV energy band. We show that the centroid of the ensemble of Kα lines, the Kβ energy, and the ratio of the Kα1 to Kα2 components are all diagnostics of the ionization parameter of our model slabs.

Subfields: Atomic and Molecular Physics, and Optics, Mechanics of Materials, Radiation

View Paper: https://www.semanticscholar.org/paper/fc8a178432e3f29c9303fddf816876a61e3f6d4f

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Citations in the corpus

Evidence for ultra-fast outflows in radio-quiet AGNs - I. Detection and statistical incidence of Fe K-shell absorption lines (2010, background): “The energy of this transition depends on the ionization state of iron: E≃6.4–6.5 keV for Fe I–XVIII, E≃6.5–6.6 keV for Fe XIX–XXIV, E≃6.7 keV for Fe XXV and E≃6.97 keV for Fe XXVI (e.g., Kallman et al. 2004).”
X-RAY REFLECTED SPECTRA FROM ACCRETION DISK MODELS. III. A COMPLETE GRID OF IONIZED REFLECTION CALCULATIONS (2013, background): “Kallman et al. (2004) present a more detailed but similar analysis of the Fe K emission complex based on xstar simulations, which includes atomic data for Fe; however, they do not consider energy redistribution due to Compton scattering.”
Multidimensional modelling of X-ray spectra for AGN accretion disc outflows (2008, background): “We note that, although convenient, those data do not account for smoothing of the K edges by broad resonances below threshold (see Palmeri et al. 2002; Kallman et al. 2004).”
On why the iron K-shell absorption in AGN is not a signature of the local warm/hot intergalactic medium (2008, methodology): “Such a large column is inconsistent with the spectrum, as this produces a strong dip at 8–10 keV (rest frame) due to the Fe Kshell edge structure (Kallman et al 2004), which is not present in the data.”
EVIDENCE FOR ULTRA-FAST OUTFLOWS IN RADIO-QUIET ACTIVE GALACTIC NUCLEI. II. DETAILED PHOTOIONIZATION MODELING OF Fe K-SHELL ABSORPTION LINES (2011, background): “In fact, it has been demonstrated that if the adequate treatment of the decay pathways of resonances converging to the K threshold is properly taken into account, the resulting edges are not sharp but smeared and broadened (Palmeri et al. 2002; Kallman et al. 2004).”
An XMM–Newton survey of broad iron lines in Seyfert galaxies (2007, methodology): “To model such components in our spectra, we used two XSPEC-compatible model spectra generated using the photoionzation code XSTAR1 (e.g. Kallman et al. 2004).”
DISCOVERY OF ULTRA-FAST OUTFLOWS IN A SAMPLE OF BROAD-LINE RADIO GALAXIES OBSERVED WITH SUZAKU (2010, background): “The most intense spectral features expected at energies &7 keV are the inner K-shell resonances from Fe XXVI (e.g., Kallman et al. 2004).”
An X-ray spectral model for Compton-thick toroidal reprocessors (2009, background): “Additional discussion and a collection of results in the literature for these atomic parameters (including line energies) can be found in Kallman et al. (2004).”
An absorption origin for the X-ray spectral variability of MCG-6-30-15 (2008, methodology): “It is particularly important to include the best possible atomic physics calcul - tions in the absorber models: Kallman et al. (2004) have shown how improved calculations lead to bound-free edges that aresignificantly less sharp than would otherwise be obtained, and those authors point out that…”
Experimental astrophysics with high power lasers and Z pinches (2004, background): “One example is the XSTAR code Kallman et al., 1996, 2004; Bautista and Kallman, 2001; Kallman and Bautista, 2001; Boroson et al., 2003 , which calculates a steady-state model of a spherical gas cloud with a radiation source at its center.”
The Suzaku View of Highly Ionized Outflows in AGN. 1; Statistical Detection and Global Absorber Properties (2012, background): “In the case of low-moderate ionization Fe the K-edge is accompanied by higher order resonance line structure which can give the edge a subtle curved profile in CCD spectra rather than it simply being an abrupt drop in flux (Kallman et al. 2004).”
Suzaku observations of 'bare' active galactic nuclei (2012, background): “There is a fairly strong peak in the obtained distribution around ξ ∼ 300, corresponding to iron being primarily found in its Fe XIX–Fe XXI ions (Kallman et al. 2004).”
X-RAY REFLECTED SPECTRA FROM ACCRETION DISK MODELS. I. CONSTANT DENSITY ATMOSPHERES (2010, methodology): “The energy position of the absorption edge indicates that is likely to be produced by Fe xiii-xiv, according to the energies presented in Kallman et al. (2004) (see in particular their Figure 2).”