Monster black holes are silencing star formation across the universe

"Traditionally, people have thought that because galaxies are so far apart, they evolve largely on their own," said Zhu, the study's lead author, whose findings were published in The Astrophysical Journal Letters. "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."

Zhu describes this concept as a "galaxy ecosystem," comparing it to interconnected ecosystems on Earth. "An active supermassive black hole is like a hungry predator dominating the ecosystem," he said. "Simply put, it swallows up matter and influences how stars in nearby galaxies grow."

What Makes Supermassive Black Holes So Powerful

Black holes have fascinated scientists and the public since they were first proposed in the early 1900s. These objects represent some of the most extreme conditions in the universe, with gravity so strong that nearby matter and even light can be pulled in if they get too close.

A special category known as supermassive black holes, including the one at the center of the Milky Way, can contain millions or even billions of times the mass of the sun. Although black holes themselves cannot be seen, they can become incredibly bright when actively consuming surrounding material.

During this active phase, known as a quasar, gas and dust form a spinning disk around the black hole, releasing enormous amounts of energy as it falls inward. These quasars can shine so intensely that they outshine their entire host galaxy.

JWST Mystery Leads to a New Discovery

Early data from the James Webb Space Telescope revealed something unexpected. Astronomers noticed that regions around some of the brightest quasars in the early universe appeared to contain fewer galaxies than anticipated. Since large galaxies typically form in dense clusters, this raised questions.

"We were puzzled," said Zhu. "Was the expensive JWST broken?" he added with a laugh. "Then we realized the galaxies might actually be there, but difficult to detect because their very recent star formation was suppressed."

This insight led researchers to consider a new possibility. Perhaps the intense radiation from quasars was not only affecting their own galaxies, but also limiting star formation in nearby ones.

Evidence That Quasars Suppress Star Formation

To explore this idea, the research team focused on one of the brightest known quasars, J0100+2802. This object is powered by a supermassive black hole with a mass about 12 billion times that of the sun. Because its light has traveled for more than 13 billion years, it provides a glimpse into the universe when it was less than a billion years old.

Using JWST, the team measured emissions from O III, an ionized form of oxygen that signals recent star formation. They found that galaxies within about a million light-years of the quasar showed weaker O III emissions compared to their ultraviolet light. This pattern indicates that star formation had recently been suppressed in those 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," said Zhu. "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."

How Radiation Disrupts Star Birth

Stars form under very specific conditions, relying on large amounts of cold molecular hydrogen gas. This gas acts as the raw material for building new stars. Scientists already knew that quasars can destroy this gas within their own galaxies, effectively shutting down local star formation.

What had remained uncertain was whether this effect extended beyond a single galaxy. By observing a quasar from the early universe, the researchers found strong evidence that this influence reaches much farther than previously thought.

"For the first time, we have evidence that this radiation impacts the universe on an intergalactic scale," said Zhu, "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."

Why JWST Was Essential

According to Zhu, this discovery would not have been possible without the James Webb Space Telescope. Light from extremely distant objects such as J0100+2802 has been stretched into infrared wavelengths due to the expansion of the universe. Earlier telescopes could not clearly detect this faint infrared light.

JWST's advanced sensitivity allows astronomers to observe these early cosmic events in unprecedented detail, opening a new window into how galaxies formed and evolved.

What This Means for the Milky Way and Beyond

The Milky Way itself may have once gone through a quasar phase, although it is not active today. Researchers are now considering how such a phase might have influenced the development of our galaxy and its neighbors.

Looking ahead, the team plans to study additional quasars to determine whether this phenomenon is widespread. They also aim to better understand the mechanisms behind these interactions and whether other factors play a role.

"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."