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Description
We have determined the relation between the AGN luminosities at rest-frame 6{mu}m associated with the dusty torus emission and at 2-10keV energies using a complete, X-ray-flux-limited sample of 232 AGN drawn from the Bright Ultra-hard XMM-Newton Survey. The objects have intrinsic X-ray luminosities between 10^42^ and 10^46^erg/s and redshifts from 0.05 to 2.8. The rest-frame 6{mu}m luminosities were computed using data from the Wide-field Infrared Survey Explorer and are based on a spectral energy distribution decomposition into AGN and galaxy emission. The best-fitting relationship for the full sample is consistent with being linear, L_6{mu}m_{prop.to}L_2-10keV_^0.99+/-0.03^, with intrinsic scatter, {Delta}logL_6{mu}m_~0.35dex. The L_6{mu}m_/L_2-10keV_ luminosity ratio is largely independent of the line-of-sight X-ray absorption. Assuming a constant X-ray bolometric correction, the fraction of AGN bolometric luminosity reprocessed in the mid-IR decreases weakly, if at all, with the AGN luminosity, a finding at odds with simple receding torus models. Type 2 AGN have redder mid-IR continua at rest-frame wavelengths <12{mu}m and are overall ~1.3-2 times fainter at 6{mu}m than type 1 AGN at a given X-ray luminosity. Regardless of whether type 1 and type 2 AGN have the same or different nuclear dusty toroidal structures, our results imply that the AGN emission at rest-frame 6{mu}m is not isotropic due to self-absorption in the dusty torus, as predicted by AGN torus models. Thus, AGN surveys at rest-frame ~6{mu}m are subject to modest dust obscuration biases.
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