The jet/disk connection in blazars
  The new high energy data coming mainly from the Fermi and Swift satellites
and from the ground based Cerenkov telescopes are making possible to study not
only the energetics of blazar jets, but also their connection to the associated
accretion disks. Furthermore, the black hole mass of the most powerful objects
can be constrained through IR-optical emission, originating in the accretion
disks. For the first time, we can evaluate jet and accretion powers in units of
the Eddington luminosity for a large number of blazars. Firsts results are
intriguing. Blazar jets have powers comparable to, and often larger than the
luminosity produced by their accretion disk. Blazar jets are produced at all
accretion rates (in Eddington units), and their appearance depends if the
accretion regime is radiatively efficient or not. The jet power is dominated by
the bulk motion of matter, not by the Poynting flux, at least in the jet region
where the bulk of the emission is produced, at ~1000 Schwarzschild radii. The
mechanism at the origin of relativistic jets must be very efficient, possibly
more than accretion, even if accretion must play a crucial role. Black hole
masses for the most powerful jets at redshift ~3 exceed one billion solar
masses, flagging the existence of a very large population of heavy black holes
at these redshifts.
