Discovery of a powerful >1061 erg AGN outburst in the distant galaxy cluster SPT-CLJ0528-5300.

• Published in: The Astrophysical Journal
• Main Authors: Calzadilla, Michael S., McDonald, Michael, Bayliss, Matthew, Benson, Bradford A., Bleem, Lindsey E., Brodwin, Mark, Edge, Alastair C., Floyd, Benjamin, Gupta, Nikhel, Hlavacek-Larrondo, Julie, McNamara, Brian R., Reichardt, Christian L.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: IOP Publishing 2019
• Subjects: South Pole; South pole
• Online Access: http://dro.dur.ac.uk/30091/; http://dro.dur.ac.uk/30091/1/30091.pdf; https://doi.org/10.3847/2041-8213/ab5b07

We present ~103 ks of Chandra observations of the galaxy cluster SPT-CLJ0528-5300 (SPT0528, z = 0.768). This cluster harbors the most radio-loud (L 1.4GHz = 1.01 × 1033 erg s−1 Hz−1) central active galactic nucleus (AGN) of any cluster in the South Pole Telescope (SPT) Sunyaev–Zeldovich 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 Australia Telescope Compact Array radio data. The combined probability that two such depressions—each at ~1.4–1.8σ significance, oriented ~180° apart and aligned with the jet axis—would occur by chance is 0.1%. At gsim1061 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 ~ 0.8), providing an avenue for studying the evolution of extreme AGN feedback. The ratio of the cavity power (${P}_{\mathrm{cav}}=(9.4\pm 5.8)\times {10}^{45}$ erg s−1) to the cooling luminosity (L cool = (1.5 ± 0.5) × 1044 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.