The Fe Kα line in reflection dominated spectra of active galactic nuclei Original Research Article

In the framework of a quasi-spherical accretion model, we present preliminary results of detailed transfer calculations and Monte Carlo simulations showing the possible importance of multiple reflections and Compton scattering on/in a photoionized plasma, for the interpretation of the iron K line complex observed in several Seyfert galaxies. We computed both line and continuum emission resulting from the reprocessing of a primary continuum in a Thomson-thick shell of clouds subtending a large solid angle (ω/4π0.9) to a central point like source. When the clouds are significantly ionized (ξ ≳100, ξ =L/nR2), an energy dependent amplification of the primary radiation occurs and must be taken into account. We find that one-ξ models cannot explain both the profile and equivalent width observed in MCG-6-30-15. However, a “two-phase mirror”, allowing for the presence of both low and high ionization clouds, seems compatible with available X-ray data. Assuming this is the main broadening mechanism, it is possible to constrain the state and distribution of the plasmas contributing to the observed profile.