  Radio plasma injected by active radio galaxies into clusters of galaxies
quickly becomes invisible due to radiative losses of the relativistic
electrons. In this talk, the fate of radio plasma and its role for the galaxy
cluster is discussed: buoyancy removes it from the central regions and allows
to transfer its energy into the ambient gas. The remaining low energy electron
populations are still able to emit a low luminosity glow of observable
radiation via synchrotron-self Comptonized emission. Shock waves in the ambient
gas can re-ignite the radio emission.
