2012MNRAS.422..252D

We investigate the excitation mechanisms of near-infrared [Fe II] and H₂ emission lines observed in active galactic nuclei (AGNs). We built a photoionization model grid considering a two-component continuum: one component accounts for the `big bump' component peaking at 1 Ryd and another represents the X-ray source that dominates the continuum emission at high energies. Photoionization models considering as ionizing source a spectral energy distribution obtained from photometric data of Seyert 2 Mrk 1066 taken from the literature were considered.
Result. of these models were compared with a large sample of observational long-slit and Integral field Unit (IFU) spectroscopy data of the nuclear region for a sample of active objects. We found that the correlation between the observational [Fe II]λ 1.2570 µm/Paβ and {img}m/Brγ is well reproduced by our models, as are the relationships that involve the H₂emission-line ratios observed in the spectroscopic data. We conclude that heating by X-rays produced by active nuclei can be considered a common and very important mechanism of excitation of [Fe II] and H₂.