X-ray Resonance Opacity of Oxygen and Iron in Agn Mcg–6-30-15

Theoretical differential oscillator strengths related to monochromatic opacity due to Kand L-shell absorption from oxygen and iron ions are directly compared with the Chandra and XMM-Newton spectra of Seyfert 1 galaxy MCG–6-30-15 . We compute the highly resolved continuum with resonances due to O I VI and Fe XVI. It is found that the KLn (n → ∞) resonance series limits in O VI, and the lowest LMM resonance in Fe XVI, lie at the prominent ∼ 17.5Å break in the observed spectra. We also calculate and identify, for the first time, the observed gap in spectral flux at 22-23 Å in the Chandra spectra due to K → L resonant absorption features from all O-ions O I VI, potentially leading to abundance determination of several or all ionization stages; similar signature gaps may be predicted due to other elements. The precise atomic parameters are computed in the relativistic close coupling approximation using the Breit-Pauli R-matrix method. The new X-ray opacities might possibly distinguish between models of a dusty warm absorber, and/or gravitational redshift and broadening due to a massive black hole in MCG–6-30-15 . Subject headings: X-Rays : general — Ultraviolet : general — atomic processes — line: formation, identification — radiation mechanisms: thermal