Active Galaxies in the Sloan Digital Sky Survey III: from quasars to
  radio galaxies?
  In this third of a series of papers concerning active galaxies in the FIRST
and Sloan Digital Sky Surveys, we analyze the spectroscopic and radio
properties of a sample of narrow-line Active Galactic Nuclei (AGN), broad-line
Seyfert I galaxies, and Quasars in the local universe in order to investigate
the dependence of their activity on the mass, spin and accretion rates of the
supermassive black holes (SMBH) residing at the centers of their host galaxies.
  We show that galaxies hosting more massive SMBH are more likely to power
stronger and larger radio jets, and we show a strong anti-correlation between
the strength of the lines of radio emitting galaxies and their radio power.
Furthermore we show that the compactness of a jet is correlated with the epoch
of the last episode of star-formation, suggesting a link between the presence
of cold gas in a galaxy, the size of its SMBH and the radio and spectroscopic
features of its AGN. We use our large statistical sample to test the
expectations of unified models of AGN based on orientation. While confirming
that Seyfert II galaxies and radio galaxies are significantly more extincted
then Seyfert Is and nearby Quasars, we find several major inconsistencies with
such a paradigm. In particular we show a strong difference in the [OIII],[OII]
and [NII] luminosities for different spectroscopic classes, a result which
argues in favor of an evolution of the broad and narrow line regions of active
nuclei over time.
  We suggests that evolution, rather than orientation, may be the key element
in shaping the properties of active nuclei, as also suggested by the results of
high-redshift X-ray and radio surveys and we speculate on a model that may
predict this kind of evolution.
