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Paper: Unification Issues and the AGN Torus
Volume: 373, The Central Engine of Active Galactic Nuclei
Page: 415
Authors: Elitzur, M.
Abstract: Observations give strong support for the unification scheme of active galactic nuclei. Clumpiness of the toroidal obscuration is crucial for explaining the IR observations and has significant consequences for AGN classification: type 1 and type 2 viewing is an angle-dependent probability, not an absolute property. The broad-line region (BLR) and the dusty torus are, respectively, the inner and outer segments, across the dust sublimation radius, of a continuous cloud distribution. Continuum X-ray obscuration comes mostly from the inner, BLR clouds. All clouds are embedded in a disk wind, whose mass outflow rate is diminishing as the accretion rate (i.e., AGN luminosity) is decreasing. The torus disappears when L≤ 1042 ergs s−1, the BLR at some lower, yet-to-be-determined luminosity.
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