The relationship between the properties of PAHs and AGN activities in type-I AGNs

In order to explore the relationship between properties of Polycyclic Aromatic Hydrocarbons (PAHs) and AGN activities in Type-I AGNs, we compiled a sample of 47 Type-I AGNs with measured PAH 11.3 μ m and 7.7 μm emission lines. The PAH emission and optical properties of these AGNs are taken from the literature. It is found that the equivalent width (EW) of 11.3 μ m emission from PAHs shows a weak correlation with the ratio of the EWs of the FeII complex between λ4434 and λ4684 to H β (RFe). The PAH 11.3/7.7 ratio is correlated with various elements defined by the first eigenvector space, which are RFe, [OIII]λ5007 luminosity and H β asymmetry. These correlations infer that AGNs with high RFe, weak [OIII] emission and a strong H β blue-wing are likely to have low PAH ionization, and hence a larger amount of neutral PAHs.