Blue Fermi Flat Spectrum Radio Quasars
  Many blazars detected by the Fermi satellite, observed spectroscopically in
the optical, are line-less, and have been classified as BL Lac objects.
Optical-UV photometry of nearly one hundred of them allowed to determine the
redshift for a handful of objects and redshift upper limits for the great
majority. A few of these are candidates to be "blue quasars", namely flat
spectrum radio quasars whose broad emission lines are hidden by an overwhelming
synchrotron emission peaking in the UV. This implies that the emitting
electrons have high energies. In turn, this requires relatively weak radiative
cooling, a condition that can be met if the main radiative dissipation of the
jet power occurs outside the broad line region. We confirm this hypothesis by
studying and modelling the spectral energy distributions of the 4 "blue
quasars" recently discovered. Furthermore, we discuss the distribution of Fermi
blazars in the gamma-ray spectral index -- gamma-ray luminosity plane, and
argue that "blue quasars" objects are a minority within the blazar populations.
