  Active Galactic Nuclei are powered by accretion onto massive black holes.
Although radio-quiet objects are not as spectacular sources of very high energy
photons as radio-loud ones this class of objects also represents a challenge
for modeling high energy processes close to a black hole. Both a hot optically
thin plasma and a cooler optically thick accretion disk are usually thought to
be present in the vicinity of a black hole although the details of the
accretion flow are still under discussion. The role of the disk seems to
decrease with a drop in the Eddington ratio: in sources like quasars and Narrow
Line Seyfert 1 galaxies disk flow dominates while in Seyfert galaxies the disk
retreats, and in sources like LINERS or Sgr A* a disk is most likely absent.
Shocks and reconnections are possibly taking place in an inner hot flow and in
the magnetic corona above the cold disk. Uncollimated outflow is also present
and it may carry significant fraction of available mass and energy.
