Deep Chandra observations of the Hydra A Cluster reveal a feature in the X-ray surface brightness that surrounds the 330 MHz radio lobes of the AGN at the cluster center .
Surface brightness profiles of this feature and its close association with the radio lobes argue strongly that it is a shock front driven by the expanding radio lobes .
The Chandra image also reveals other new structure on smaller scales that is associated with the radio source , including a large cavity and filament .
The shock front extends 200 – 300 kpc from the AGN at the cluster center and its strength varies along the front , with Mach numbers in the range \sim 1.2 – 1.4 .
It is stronger where it is more distant from the cluster center , as expected for a shock driven by expanding radio lobes .
Simple modeling gives an age for the shock front \sim 1.4 \times 10 ^ { 8 } y and a total energy driving it of \sim 10 ^ { 61 } erg .
The mean mechanical power driving the shock is comparable to quasar luminosities , well in excess of that needed to regulate the cooling core in Hydra A .
This suggests that the feedback regulating cooling cores is inefficient , in that the bulk of the energy is deposited beyond the cooling core .
In that case , a significant part of cluster “ preheating ” is a byproduct of the regulation of cooling cores .