Cluster Cooling Flows in the Chandra Era
Brian McNamara (Ohio U)
The giant cD galaxies located at the centers of galaxy clusters are
often the sites of massive bursts of star formation. These starbursts
occur preferentially in so-called cooling flow clusters, where the
hot, X-ray-emitting intracluster medium appears to cool at rates of
several hundred solar masses per year. X-ray images of cooling flow
clusters taken with the Chandra X-ray Observatory show that the gas is
cooling at rates that are considerably smaller than those from earlier
missions. In addition, the Chandra imaging shows that cluster cores
can be remarkably complex. I will present exciting new evidence that
radio sources have a major impact on the structure of the intracluster
medium. In some instances the radio sources are displacing the gas,
leaving cavities supported by magnetic fields, cosmic rays, and
perhaps a dilute, hot plasma. In addition, radio-faint, ``ghost''
cavities are seen in some clusters which may be relics of earlier
radio outbursts. Radio sources may be capable of substantially
reducing or quenching cooling flows, while at the same time triggering
bursts of star formation in the residual cooling gas.
