AGNs Are Not That Cool: Revisiting the Intrinsic AGN Far-infrared Spectral Energy Distribution

Abstract

Abstract We investigate the intrinsic spectral energy distribution (SED) of active galactic nuclei (AGNs) at infrared (IR) bands with 42 z < 0.5 optically luminous Palomar Green survey quasars through SED decomposition. We decompose the SEDs of the 42 quasars by combining an AGN IR template library that covers a wide range of the AGN parameter space with three commonly used galaxy template libraries. We determine the median AGN SED from the best-fitting results. The far-IR (FIR) contribution of our median AGN SED is significantly smaller than that of Symeonidis et al., but roughly consistent with that of Lyu & Rieke. The AGN IR SED becomes cooler with increasing bolometric luminosity, which might be due to the fact that more luminous AGNs might have stronger radiative feedback to change torus structures and/or their tori might have higher metallicities. Our conclusions do not depend on the choice of galaxy template libraries. However, as the predicted polycyclic aromatic hydrocarbon (PAH) emission line flux is galaxy template dependent, cautions should be taken on deriving galaxy FIR contribution from PAH fluxes.