High redshift Fermi blazars observed by GROND and Swift
  We observed 5 gamma-ray loud blazars at redshift greater than 2 with the
X-Ray Telescope (XRT) and the UltraViolet and Optical Telescope (UVOT) onboard
the Swift satellite, and the Gamma-Ray burst Optical Near-Infrared Detector
(GROND) instrument. These observations were quasi simultaneous, usually within
a few hours. For 4 of these blazars the near-IR to UV data show the presence of
an accretion disc, and we could reliably estimate its accretion rate and black
hole mass. One of them, PKS 1348+007, was found in an extraordinarily high
IR-optical state, almost two orders of magnitude brighter than at the epoch of
the Sloan Digital Sky Survey observations. For all the 5 quasars the physical
parameters of the jet emitting zone, derived by applying a one-zone emission
model, are similar to that found for the bulk of other gamma-ray loud quasars.
With our observations we have X-ray data for the full sample of blazars at z>2
present in the Fermi 2-yrs (2LAC) catalog. This allows to have a rather
complete view of the spectral energy distribution of all high-redshift Fermi
blazars, and to draw some conclusions about their properties, and especially
about the relation between the accretion rate and the jet power.
