EW [OIII] as an orientation indicator

Abstract

We present an analysis of the average spectral properties of 12,000 SDSS quasars as a function of accretion disk inclination, as measured from the equivalent width of the [O III] 5007Å line. The use of this indicator on a large sample of quasars from the SDSS DR7 has proven the presence of orientation effects on the features of UV/optical spectra, confirming the presence of outflows in the NLR gas and that the geometry of the BLR is disk-like. Relying on the goodness of this indicator, we are now using it to investigate other bands/components of AGN. Specifically, the study of the UV/optical/IR SED of the same sample provides information on the obscuring “torus”. The SED shows an increase of the IR fraction moving from face-on to to edge-on positions, in agreement with models where the torus is coaxial with the accretion disk, and characterised by a clumpy structure.