AGN feedback and its quenching efficiency
  In the last decade, observations have accumulated on gas outflows in
galaxies, and in particular massive molecular ones. The mass outflow rate is
estimated between 1-5 times the star formation rate. For the highest maximal
velocities, they are driven by AGN; these outflows are therefore a clear way to
moderate or suppress star formation. Some of the most convincing examples at
low redshift come from the radio mode, when the radio jets are inclined towards
the galaxy plane, or expand in the hot intra-cluster medium, in cool core
clusters. However, AGN feedback can also be positive in many occasions, and the
net effect is difficult to evaluate. The quenching efficiency is discussed in
view of recent observations.
