  Almost every strong cooling core contains an active radio galaxy. Combined
radio and X-ray images reveal the dramatic interaction which is taking place
between the radio jet and the central cluster plasma. At least two important
questions can in principle be answered by comparing the new data to theoretical
models. The first is how the radio jet propagates, and disrupts, in the cooling
core environment: why are these cluster-center radio sources unusual? The
second is the effect the radio jet has on the cooling core: is it energetically
important to the core? Thanks to the new data we are beginning to be able to
answer these questions.
