Chandra X-ray Observatory, Perseus Cluster (2003)
Chandra found giant cavities and bubbles in the hot X-ray gas of the Perseus cluster, carved by jets from the central supermassive black hole. The cavities showed the black hole mechanically pushing gas around, not just absorbing it.
This was the first direct evidence that black holes inject energy into surrounding cluster gas, establishing the concept of active galactic nucleus feedback.
It reshaped how astronomers understand galaxy and cluster evolution, linking black hole activity to the fate of gas in their surroundings.
The Perseus discovery established the feedback framework; the H1821+643 result dramatically extends the reach of that feedback beyond the host galaxy.
