Intergalactic predators? James Webb data hints supermassive black holes may act like cosmic killers, preventing star birth in distant galaxies

‘Black holes are among the most mysterious cosmic objects, much studied but not fully understood’ this is what NASA summarizes about black holes because of their mysterious natures. For a long time, scientists believed that active supermassive black holes can shut down star formation in their host galaxies. New research published on December 3, 2025, in The Astrophysical Journal Letters now suggests their destructive influence can stretch much farther, suppressing star birth in neighboring galaxies across vast intergalactic distances.

For astronomers, a galaxy is considered “dead” when it stops forming new stars. Supermassive black holes can trigger this process when they actively feed, heating surrounding gas and dust so intensely that it is either blown away or prevented from cooling and collapsing into stars. Until now, this effect was thought to be largely confined to a black hole’s own galaxy.

“Traditionally, people have thought that because galaxies are so far apart, they evolve largely on their own,” said team leader Yongda Zhu of the University of Arizona in eurekalert. “But we found that a very active, supermassive black hole in one galaxy can affect other galaxies across millions of light-years, suggesting that galaxy evolution may be more of a group effort.”


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A ‘galactic ecosystem’ shaped by black holes

Zhu and his colleagues describe this far-reaching influence as a kind of “galactic ecosystem,” similar to how changes in one part of Earth’s environment can affect distant regions.

“An active supermassive black hole is like a hungry predator dominating the ecosystem,” Zhu said. “Simply put, it swallows up matter and influences how stars in nearby galaxies grow.”

Not all supermassive black holes behave this way. Many large galaxies host such objects at their centers, but only those actively consuming matter known as active galactic nuclei (AGN) release enough energy to reshape their surroundings.

For context, the closest known black hole to Earth, dubbed Gaia BH1, is a so-called “sleeping” or dormant black hole. It is not actively feeding on surrounding material or emitting dangerous radiation, has a mass about 10 times that of the Sun, and lies roughly 1,600 light-years away in the constellation Ophiuchus. That makes it three times closer to Earth than the previous record holder, an X-ray binary system located in the constellation Monoceros.

When black holes turns to quasars

Black holes, as their name suggests, are inherently invisible. However, when supermassive black holes actively consume surrounding gas and dust, they can become some of the brightest objects in the universe. In this phase, they may emit hundreds of trillions of times more energy than the Sun, appearing as intense points of light in telescope images.

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Astronomers call these objects quasars, a stage in a black hole’s life when infalling matter forms a rapidly spinning accretion disk. As material spirals inward, extreme heat and friction release vast amounts of energy, often causing the quasar to outshine every star in its host galaxy combined.

James Webb observations raise new questions

Since the launch of the James Webb Space Telescope, astronomers have noticed a puzzling pattern: the most powerful quasars often appear to have surprisingly few nearby galaxies. That is unusual, because large galaxies typically form in clusters.

“We were puzzled,” Zhu said. “Then we realized the galaxies might actually be there but difficult to detect because their very recent star formation was suppressed.”

A case study of a powerful quasar

To test this idea, the team studied one of the brightest quasars ever observed, J0100+2802. The quasar existed when the universe was less than a billion years old and is powered by a supermassive black hole roughly 12 billion times the mass of the sun.

Using JWST data, the researchers searched for signs of ionized oxygen, a key indicator of recent star formation, in galaxies surrounding the quasar. They found significantly less of this signal within about one million light-years of J0100+2802 compared with more distant galaxies.

“Black holes are known to ‘eat’ a lot of stuff, but during the active eating process and in their luminous quasar form, they also emit very strong radiation,” Zhu said. “The intense heat and radiation split the molecular hydrogen that makes up vast interstellar gas clouds, quenching its potential to accumulate and turn into new stars.”

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“For the first time, we have evidence that this radiation impacts the universe on an intergalactic scale,” he added. “Quasars don't just suppress stars in their host galaxies but also in nearby galaxies within a radius of at least a million light-years.”

Implications for galaxy evolution

The team plans to study additional quasar fields to determine how widespread this effect may be. Understanding how galaxies influenced one another in the early universe could also shed light on how our own galaxy formed.

“Understanding how galaxies influenced one another in the early universe helps us better understand how our own galaxy came to be,” Zhu said. “Now we realize that supermassive black holes may have played a much larger role in galaxy evolution than we once thought - acting as cosmic predators, influencing the growth of stars in nearby galaxies during the early universe.”