Bibcode
Ichikawa, K.; Packham, Christopher; Ramos Almeida, C.; Asensio Ramos, A.; Alonso-Herrero, Almudena; González-Martín, O.; Lopez-Rodriguez, Enrique; Ueda, Yoshihiro; Díaz-Santos, Tanio; Elitzur, Moshe; Hönig, Sebastian F.; Imanishi, Masatoshi; Levenson, Nancy A.; Mason, Rachel E.; Perlman, Eric S.; Alsip, Crystal D.
Bibliographical reference
The Astrophysical Journal, Volume 803, Issue 2, article id. 57, 12 pp. (2015).
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2015
Journal
Citations
91
Refereed citations
83
Description
We present results from the fitting of infrared (IR) spectral energy
distributions of 21 active galactic nuclei (AGNs) with clumpy torus
models. We compiled high spatial resolution (∼0.3–0.7 arcsec)
mid-IR (MIR) N-band spectroscopy, Q-band imaging, and nuclear near- and
MIR photometry from the literature. Combining these nuclear near- and
MIR observations, far-IR photometry, and clumpy torus models enables us
to put constraints on the torus properties and geometry. We divide the
sample into three types according to the broad line region (BLR)
properties: type-1s, type-2s with scattered or hidden broad line region
(HBLR) previously observed, and type-2s without any published HBLR
signature (NHBLR). Comparing the torus model parameters gives us the
first quantitative torus geometrical view for each subgroup. We find
that NHBLR AGNs have smaller torus opening angles and larger covering
factors than HBLR AGNs. This suggests that the chance to observe
scattered (polarized) flux from the BLR in NHBLR could be reduced by the
dual effects of (a) less scattering medium due to the reduced scattering
volume given the small torus opening angle and (b) the increased torus
obscuration between the observer and the scattering region. These
effects give a reasonable explanation for the lack of observed HBLR in
some type-2 AGNs.
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