A Dead Galaxy From the Early Universe Succumbed to Starvation Due to its Own Black Hole

Scattered throughout the universe, colossal galaxies appear dead, unable to form new stars. One of the oldest dead galaxies has recently been studied, confirming that its death sentence was handed down by a black hole that reduced its main stellar resource.

A new study published in Natural astronomy revealed how GS-10578, also known as “Pablo’s Galaxy” after the astronomer who first observed it in detail, was decommissioned. The black hole at its center gradually warmed the cold gas of the galaxy, an element necessary for the formation of stars. Pablo’s galaxy has been deprived of this gas over time – a similar result could happen everywhere in the universe, as astronomers discover more and more galaxies that appear surprisingly old and contain stars that formed shortly after the Big Bang.

Learn more: Astronomers looked back 12 billion years and discovered a galaxy cluster that defies theory

Live fast and die young

Pablo’s galaxy was born in the early stages of the universe, with most of its stars forming between 12.5 and 11.5 billion years ago — the Big Bang, for reference, happened 13.8 billion years ago. For an ancient galaxy, it is also surprisingly massive, about 200 billion times the mass of our sun.

But Pablo’s galaxy is one whose life quickly died out, according to the new study’s researchers; they say he appears to have “lived fast and died young.”

The ephemeral history of this galaxy has been captured in data from the James Webb Space Telescope (JWST) and the Atacama Large Millimeter Array (ALMA). Based on their observations, the researchers believe that the supermassive black hole at the heart of the galaxy caused continued decline rather than abrupt destruction.

Lack of star making materials

In any galaxy, cold gas is needed to restart star formation. But when researchers looked for signs of cold gas in the Pablo Galaxy, they found that it was dry. Observing with ALMA for almost seven hours, they were unable to detect carbon monoxide, associated with the presence of cold hydrogen gas.

Further observations with JWST spectroscopy revealed what likely happened to Pablo’s galaxy: powerful winds of neutral gas from the galaxy’s supermassive black hole diminished the supply of cold gas. The winds, traveling at 400 kilometers per second, carry away 60 solar masses of gas each year, according to the researchers. At this rate, the galaxy’s remaining fuel was exhausted in just 16 to 220 million years, which normally takes more than a billion years for other galaxies.

“The galaxy looks like a quiet, rotating disk,” co-first author Francesco D’Eugenio, an astrophysicist at the Kavli Institute of Cosmology, said in a statement. “This tells us that it did not undergo a major, disruptive merger with another galaxy. Yet it stopped forming stars 400 million years ago, while the black hole was active again. So the current black hole activity and gas explosion we observed did not cause the shutdown; instead, repeated episodes likely prevented the fuel from returning.”

The fate of the first galaxies

The researchers determined that Pablo’s galaxy had evolved with zero net input, meaning it had reached a point where it was no longer replenished with fresh gas. They think the black hole heated or expelled the incoming gas over several cycles, depriving the galaxy of the resources it needed to continue making stars.

Pablo’s galaxy may not be the only galaxy starving. Many recently discovered galaxies that appear massive and ancient have raised questions for astronomers.

“Before Webb, this was unheard of,” said co-first author Jan Scholtz, an astrophysicist at the University of Cambridge and the Kavli Institute. “Now we know they are more common than we thought – and this starvation effect could explain why they live fast and die young.”

The researchers say future studies could show that death by starvation could be a common theme in these galaxies that formed in the early universe.

Learn more: The size of our galaxy spans tens of thousands of light years, but its height is rather small

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