The near-to-mid infrared spectrum of quasars
  We analyse a sample of 85 luminous (log(nuLnu(3\um)/erg s-1)>45.5) quasars
with restframe ~2-11 \um spectroscopy from AKARI and Spitzer. Their high
luminosity allows a direct determination of the near-infrared quasar spectrum
free from host galaxy emission. A semi-empirical model consisting of a single
template for the accretion disk and two blackbodies for the dust emission
successfully reproduces the 0.1-10 \um spectral energy distributions (SEDs).
Excess emission at 1-2 \um over the best-fitting model suggests that hotter
dust is necessary in addition to the ~1200 K blackbody and the disk to
reproduce the entire near-infrared spectrum. Variation in the extinction
affecting the disk and in the relative strength of the disk and dust components
accounts for the diversity of individual SEDs. Quasars with higher dust-to-disk
luminosity ratios show slightly redder infrared continua and less prominent
silicate emission. We find no luminosity dependence in the shape of the average
infrared quasar spectrum. We generate a new quasar template that covers the
restframe range 0.1-11 \um, and separate templates for the disk and dust
components. Comparison with other infrared quasar composites suggests that
previous ones are less reliable in the 2-4 \um range. Our template is the first
one to provide a detailed view of the infrared emission on both sides of the 4
\um bump.
