The disk-torus system in active galactic nuclei: possible evidence of
  highly spinning black holes
  We study the ratio $R$ between the luminosity of the torus and that of the
accretion disk, inferred from the relativistic model KERRBB for a sample of
approximately 2000 luminosity-selected radio-quiet Type I active galactic
nuclei from the Sloan Digital Sky Survey catalog. We find a mean ratio $R
\approx 0.8$ and a considerable number of sources with $R \gtrsim 1$. Our
statistical analysis regarding the distribution of the observed ratios suggests
that the largest values might be linked to strong relativistic effects due to a
large black hole spin ($a > 0.8$), despite the radio-quiet nature of the
sources. The mean value of $R$ sets a constraint on the average torus aperture
angle (in the range $30^{\circ} < \theta_{\rm T} < 70^{\circ}$) and, for about
one-third of the sources, the spin must be $a > 0.7$. Moreover, our results
suggest that the strength of the disk radiation (i.e., the Eddington ratio)
could shape the torus geometry and the relative luminosity ratio $R$. Given the
importance of the involved uncertainties on this statistical investigation, an
extensive analysis and discussion have been made to assess the robustness of
our results.
