We present { \sim } 103 ks of Chandra observations of the galaxy cluster SPT-CLJ0528-5300 ( SPT0528 , z { = } 0.768 ) .
This cluster harbors the most radio-loud ( L _ { 1.4 GHz } { = } ~ { } 1.01 { \times } 10 ^ { 33 } erg s ^ { -1 } Hz ^ { -1 } ) central AGN of any cluster in the South Pole Telescope ( SPT ) SZ survey with available X-ray data .
We find evidence of AGN-inflated cavities in the X-ray emission , which are consistent with the orientation of the jet direction revealed by ATCA radio data .
The combined probability that two such depressions – each at { \sim } 1.4 - 1.8 \sigma significance , oriented { \sim } 180 ^ { \circ } apart and aligned with the jet axis – would occur by chance is 0.1 % .
At { \gtrsim } 10 ^ { 61 } erg , the outburst in SPT0528 is among the most energetic known in the universe , and certainly the most powerful known at z { > } 0.25 .
This work demonstrates that such powerful outbursts can be detected even in shallow X-ray exposures out to relatively high redshifts ( z { \sim } 0.8 ) , providing an avenue for studying the evolution of extreme AGN feedback .
The ratio of the cavity power ( P _ { cav } { = } ~ { } 9.4 { \pm } 5.8 { \times } 10 ^ { 45 } erg s ^ { -1 } ) to the cooling luminosity ( L _ { cool } { = } ~ { } 1.5 { \pm } 0.5 { \times } 10 ^ { 44 } erg s ^ { -1 } ) for SPT0528 is among the highest measured to date .
If , in the future , additional systems are discovered at similar redshifts with equally high P _ { cav } / L _ { cool } ratios , it would imply that the feedback/cooling cycle was not as gentle at high redshifts as in the low-redshift universe .