On Fe Kα line emission by photo-ionized accretion disks Original Research Article

We discuss (1) the importance of ionization physics in the interpretation of X-ray reflection features seen in spectra of most AGN and GBHCs. We show that changes in the ionization structure of the reflector with changes in the X-ray flux or its spectral shape may be confused with changes in the geometry of the accretion flow when studied with simpler (incomplete) X-ray reflection models. (2) In addition, we point out that iron lines from time-dependent accretion disks in their “quiescent” states should be narrow even if the cold accretion disk extends to the last stable orbit.