2006A&A...457L..17H

We investigate mid-infrared and X-ray properties of the dusty torus in unification scenarios for active galactic nuclei. We use the relation between mid IR and hard X-ray luminosities to constrain AGN unification scenarios. With VISIR at the VLT, we have obtained the currently highest angular resolution (0.35" FWHM) narrow-band mid infrared images of the nuclei of 8 nearby Seyfert galaxies. Combining these observations with X-ray data from the literature we study the correlation between their mid IR and hard X-ray luminosities. We find that the rest frame 12.3µm (L_MIR) and 2-10keV (L_X) luminosities are correlated at a highly significant level. The best fit power-law to our data is logL_MIR∝(1.60±0.22)logL_X, showing a much smaller dispersion than earlier studies. The similarity in the logL_MIR/logL_X ratio between Sy1s and Sy2s even using high angular resolution MIR data implies that the similarity is intrinsic to AGN and not caused by contamination from extra-nuclear emission. This supports clumpy torus models. The exponent of the correlation constrains the inner geometry of the torus.