Heating by Radio Sources

• Earlier models (e.g. Heinz, Reynolds, & Begelman 1998) predicted that radio sources would heat the ICM through strong shocks. This heating could help to balance the cooling in cooling flows.

• Shock heating models showed that the gas found around the radio sources should be bright, dense, and hotter than the neighboring gas. This temperature rise has not been observed.

• Newer models (e.g. Reynolds, Heinz, & Begelman 2001) instead invoke weak shocks to do the heating, which can result in X-ray shells that are relatively cool.

• Buoyantly rising bubbles of radio plasma can also transport energy into clusters.