Dusty Structure Around Type-I Active Galactic Nuclei: Clumpy Torus
  Narrow Line Region and Near-Nucleus Hot Dust
  We fitted Spitzer/IRS ~2-35 um spectra of 26 luminous QSOs in attempt to
define the main emission components. Our model has three major components: a
clumpy torus, dusty narrow line region (NLR) clouds and a blackbody-like dust.
The models utilize the clumpy torus of Nenkova et al. (2008) and are the first
to allow its consistent check in type-I AGNs. Single torus models and combined
torus-NLR models fail to fit the spectra of most sources but three component
models adequately fit the spectra of all sources. We present torus inclination,
cloud distribution, covering factor and torus mass for all sources and compare
them with bolometric luminosity, black hole mass and accretion rate. The torus
covering factor and mass are found to be correlated with the bolometric
luminosity of the sources. We find that a substantial amount of the ~2-7 um
radiation originates from a hot dust component, which likely situated in the
innermost part of the torus. The luminosity radiated by this component and its
covering factor are comparable to those of the torus. We quantify the emission
by the NLR clouds and estimate their distance from the center. The distances
are ~700 times larger than the dust sublimation radius and the NLR covering
factor is about 0.07. The total covering factor by all components is in good
agreement with the known AGN type-I:type-II ratio.
