AGN torus emission for a homogeneous sample of bright FSRQs
  We have selected a complete sample of 80 flat-spectrum radio quasars (FSRQs)
from the WMAP 7-yr catalog within the SDSS area, all with measured redshift,
and have inspected their SEDs looking for evidence of an AGN torus emission. A
SED fitting algorithm has found such evidence for seven objects and an
uncertain indication for one more. These 8 FSRQs belong to the sub-sample of 55
sources showing the optical--ultraviolet bump interpreted as thermal emission
from a standard accretion disc. Torus luminosities have been estimated for the
eight objects whose torus was identified by the fitting algorithm. For the
other 47 FSRQs in the sub-sample we have derived upper limits to the torus
luminosity. Our analysis shows that the torus can show up clearly only under
quite special conditions: low luminosity and preferentially low peak frequency
of the beamed synchrotron emission from the jet; high torus luminosity, close
to that of the accretion disc. This implies that the inferred ratios of torus
to disc luminosity are biased high. The median value, considering upper limits
as detections, is $L_{\rm torus}/L_{\rm disc}\sim 1$ while studies of radio
quiet quasars yield average ratios $\langle L_{\rm torus}/L_{\rm disc}\rangle
\simeq 1/3-1/2$. Our results are compatible with the FSRQ tori having the same
properties of those of radio quiet quasars. At variance with Plotkin et al.
(2012), who investigated a sample of optically selected BL Lacs, we find that
the Wide-field Infrared Survey Explorer (WISE) infrared colors do not allow us
to draw any conclusion on the presence or absence of tori associated with WMAP
selected blazars. With the latter selection blazars of all types (FSRQs with
and without evidence of torus, BL Lacs, blazars of unknown type) occupy the
same region of the WISE color-color plane, and their region overlaps that of
SDSS quasars with point-like morphology.
