Hot-Dust-Poor Quasars in Mid-Infrared and Optically Selected Samples
  We show that the Hot-Dust-Poor (HDP) quasars, originally found in the X-ray
selected XMM-COSMOS type 1 AGN sample, are just as common in two samples
selected at optical/infrared wavelengths: the Richards et al. Spitzer/SDSS
sample ($8.7%\pm2.2%$), and the PG-quasar dominated sample of Elvis et al.
($9.5%\pm 5.0%$). The properties of the HDP quasars in these two samples are
consistent with the XMM-COSMOS sample, except that, at the $99% (\sim
2.5\sigma)$ significance, a larger proportion of the HDP quasars in the
Spitzer/SDSS sample have weak host galaxy contributions, probably due to the
selection criteria used. Either the host-dust is destroyed (dynamically or by
radiation), or is offset from the central black hole due to recoiling.
Alternatively, the universality of HDP quasars in samples with different
selection methods and the continuous distribution of dust covering factor in
type 1 AGNs, suggest that the range of SEDs could be related to the range of
tilts in warped fueling disks, as in the model of Lawrence and Elvis (2010),
with HDP quasars having relatively small warps.
