Triggering of Feedback in Galaxy Cluster Cores
Mark Voit



The long-standing cooling-flow problem in galaxy clusters is now partially solved. Feedback from a central active galactic nucleus appears to be resupplying the energy radiated from cluster cores and preventing overproduction of stars in the central galaxy. However, much about this process remains mysterious. For example, somehow the accretion rate on parsec scales in the vicinity of the central engine is tuned to match the intracluster cooling rate on scales of tens of kiloparsecs. My talk will discuss the observational evidence pointing to the conditions for triggering feedback in galaxy cluster cores and the roles of conduction and thermal instability in regulating that feedback.