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The young galaxy GS-10578 seen by JWST is starved to death by its supermassive black hole. |Image source: JADES cooperation
Astronomers have discovered that a young galaxy gradually becomes starved of its central supermassive black hole, effectively killing the universe by a thousand cuts.
James Webb Space Telescope (John West) and the Atacama Large Millimeter/submillimeter Array (Alma) studied this unfortunate galaxy, known as GS-10578 or the slightly more playful nickname “Pablo’s Galaxy” in honor of the first astronomer to study it in detail. The light from Pablo’s galaxy took about 11 billion years to reach us, which means JWST and ALMA allowed astronomers to see it as it arrived after 3 billion years. big Bang. It is unusually massive for such an early galaxy, with a mass equivalent to about 200 billion suns.
Most of the stars in the Pablo Galaxy appear to have formed between 12.5 and 11.5 billion years ago. However, despite the galaxy’s relative youth, it appears to have stopped forming stars and has exhausted its supply of cold star-forming gas. Astronomers define the cessation of star formation and the transition into quiescence as the “death” of a galaxy, meaning that Pablo’s galaxy “lives fast and dies young.”
The team behind the study first published results on Pablo’s galaxy September 2024using JWST alone, found supermassive black hole At its core, it expels large amounts of gas at 2.2 million miles per hour (3.5 million kilometers per hour). This speed is enough for this star-forming material to completely escape the gravitational influence of Pablo’s galaxy.
Together with ALMA, an array of 66 radio telescopes in the Atacama Desert region of northern Chile, the researchers observed the Pablo Galaxy for another seven hours, looking for carbon monoxide, which they could use to track cold hydrogen gas (the material that forms stars). However, the search came up empty handed.
But that speaks volumes in itself.
“What surprised us was how much you can learn even if you can’t see something,” said team member Jan Scholtz from the University of Cambridge in the UK. said in a statement. “Even ALMA’s deepest observations of such galaxies left essentially no cold gas behind. This suggests a slow starvation rather than a dramatic fatal blow.”
Meanwhile, a further 6.5 hours of observations by JWST revealed that the Pablo Galaxy is losing gas mass equivalent to 60 solar masses per year. At this rate, the fuel for star formation in the galaxy could be exhausted in 16 million to 220 million years. If that seems like an incredibly long time, consider that scientists typically estimate that it takes up to a billion years to run out of fuel for star formation in a galaxy like this.
“This galaxy looks like a calm, rotating disk,” said team co-leader Francesco De Eugenio of the Kaveri Institute of Cosmology. “This tells us that it did not undergo a major, destructive merger with another galaxy. However, it ceased star formation 400 million years ago, and the black hole became active again.”
The team reconstructed the star formation history of Pablo’s galaxy and found that the black hole pushed gas outward, preventing fresh gas from falling back into the galaxy. This prevents the “fuel tank” of star birth from being refilled. They also found that the supermassive black hole in this young galaxy did not expel all the gas at once, but instead kept going through repeated cycles of gas expulsion.
“Thus, the current black hole activity and outbursts of gas we observe are not causing a shutdown; instead, recurring events may prevent fuel from returning,” De Eugenio added.
The team’s findings may help explain why JWST found many ancient-looking galaxies in the early universe.
“You don’t need a catastrophe to stop a galaxy from forming stars, you just need to stop fresh fuel from getting in. Before Webb, these were unheard of,” Scholz said. “Now we know they are more common than we thought – this starvation effect may be why they live faster and die younger.”
As the effectiveness of the ALMA/JWST telescope team is established, astronomers hope that further observations of Pablo’s galaxy will reveal more about the mechanisms by which supermassive black holes starve the galaxy to its premature death.
The team’s findings were published in the journal on Tuesday (November 25) Natural Astronomy.