Multiple photoionization for the Fe⁺ 2p subshell

Photoionization plays a key role in the production of highly charged ions in active galactic nuclei (AGNs). The inner shell photoionization leads to highly excited states that are the subject of radiative and Auger cascade. An electron from a higher shell fills the inner-shell vacancy while simultaneously causing the removal of another electron from the atomic system during the Auger decay. As a result of the Auger cascade, the produced ions have higher charge states than the initial ion. However, the final ion population eventually stabilizes in states that are below the ionization threshold of the corresponding ion. The aim of the current work is to study multiple photoionization of the 2p subshell of the Fe⁺ 3d⁶4s configuration. The investigation of multiple photoionization for the iron atom and ions was the subject of our earlier work [1, 2], and this study represents a continuation of that research. The Fe⁺ ion is an important diagnostic tool for the study of AGNs. The Fe⁺ emission is thought to arise from gas in the broad line region. On the other hand, the higher ionization stages of Fe were observed in spectra from AGNs [3].