SIMBAD references

We propose a new diagnostic of the ``dusty torus'' model for Seyfert nuclei. Dust grains in the torus are heated by the nuclear continuum and reradiate mostly in the mid-infrared wavelengths. From the geometry of the torus, it is predicted that the emission at λ≤10 µm has strong dependence on the viewing angle. Since the dependence is predicted to be insignificant at λ≥10 µm, we study the flux ratio between 3.5 µm (L band) and 25 µm; R(L,25)=log[(ν_3.5µmS(ν_3.5µm))/(ν_25µmS(ν_25µm))]. In three different samples (optically selected, X-ray-selected, and infrared-selected samples) of Seyfert galaxies, the observed values of R(L, 25) between type 1 Seyfert galaxies (S1's) and type 2 Seyfert galaxies (S2's) are found to be clearly separated; R(L, 25)>-0.6 for S1's while R(L, 25)←0.6 for S2's. This implies universality of their torus properties. With this result and the other observational characteristics, we investigate the most plausible torus model among those presented in Pier & Krolik.