How a Supermassive Black Hole Is Slowly Starving a Galaxy to Death

Astronomers have discovered how a supermassive black hole can gradually starve a galaxy to death, rather than destroying it in a sudden burst. This was found by studying Pablo's Galaxy, a massive system that stopped forming stars around 400 million years ago, despite being only 3 billion years old.

Pablo's Galaxy, officially named GS-10578, is about 200 billion times heavier than the Sun. Researchers used the Atacama Large Millimeter Array (ALMA) to detect almost no carbon monoxide, a key indicator of cold hydrogen gas. This showed that the galaxy had been deprived of the fuel needed for star formation.

Observations from the James Webb Space Telescope (JWST) then revealed strong winds of neutral gas blowing out from the black hole at 400 kilometers per second. These outflows remove about 60 solar masses of gas each year, preventing new material from replenishing the galaxy. The team found that star formation had already stopped long before the current black hole activity, suggesting repeated cycles of heating and gas expulsion over time.

The discovery helps explain why JWST has found so many unexpectedly mature, massive galaxies in the early Universe. To explore this further, the Cambridge-led team has secured more JWST observation time. Their next goal is to study warmer hydrogen gas and investigate how supermassive black holes suppress star formation in galaxies like Pablo's.

The study demonstrates the effectiveness of combining ALMA's deep radio observations with JWST's infrared spectroscopy. This approach provides clearer insights into how black holes shape galaxy evolution. Future observations will focus on the role of warmer gas in this process, building on the evidence of slow starvation in Pablo's Galaxy.