The "Universe Destroyers" discovered by the James Webb Space Telescope may represent a new class of cosmic object: a black hole.

An image of a black hole star—a potentially new class of cosmic object with a central black hole powering it and a dense cocoon of turbulent gas surrounding it like a star. (Image credit: MPIA/HdA/T. Müller/A. de Graaff)

Astronomers have discovered a new object that could help shed light on the mysterious “little red dots” first spotted by the James Webb Space Telescope (JWST) in 2022.

According to the researchers, the newly discovered object, dubbed “The Rock,” suggests that the small red dots represent an entirely new class of cosmic objects known as “star-like black holes.” This new hypothetical object is essentially a black hole that is expanding so rapidly that it illuminates the dense gas cocoon surrounding it, causing it to glow like a star.

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However, all of these theories are still evolving, so it's unclear whether these dots are exotic objects or simply a stage in the growth of galaxies or black holes. When they were first discovered, the small red dots were dubbed “universe destroyers” because they seemed too old to have existed in the first few billion years of the universe's existence. Therefore, astronomers have looked beyond the standard types of known objects to find an explanation for what they might be.

They proposed two models. “One possibility is that the Little Red Dots are extremely massive and compact galaxies with intense star formation, resulting in very high stellar densities in their cores,” said Fabio Pacucci, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, who was not involved in the new study. This scenario suggests that the Little Red Dots are tiny but dense galaxies rich in stars, and that exotic, previously unobserved processes are occurring within them.

“Another possibility is that they harbor massive black holes at their centers, which often appear 'too massive' compared to the stellar mass of their galaxies,” he told Live Science via email. In both cases, the redness is due to the enormous amount of dust surrounding the object.

The second explanation is that the small red dots are galaxies powered by a massive black hole at their center, similar to an active galactic nucleus (AGN). These black hole-powered galaxies are completely unlike other types of AGNs discovered in the early universe, known as quasars—extremely bright objects powered by large supermassive black holes and easily detectable because they are not obscured by dust. The relationship between these two population types remains unclear.

“Both explanations expand our current understanding of the early evolution of galaxies,” Pacucci said.

Cliff hanger

In a new study published September 10 in the journal Astronomy & Astrophysics, a team of astronomers led by Anne de Graaff of the Max Planck Institute for Astronomy looked at an unusual small red dot that existed 1.8 billion years after the Big Bang.

This small red dot, whose light took nearly 12 billion years to reach us, was discovered among many other small red dots identified by the Red Unknowns: Bright Infrared Extragalactic Survey (RUBIES) conducted with the JWST.

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In the light of this object, the researchers observed a very sharp jump in brightness, called a Balmer break. Although such a brightness jump is characteristic of the light of various objects, the researchers found that the sharpness observed in the light of this object could not be explained by the presence of massive galaxies or typical active galactic nuclei. They identified it as an exaggerated version of the small red dot and dubbed it “The Rock” for its sharp jump in brightness across the spectrum.

An image showing the spectrum of light from “The Rock,” an ancient red object that may be a black hole surrounded by a shell of hot gas.

This unusually bright feature led astronomers to wonder if they had observed something entirely new. The object's brightness suggested a highly energetic source, and the Balmer gap, as de Graaff explained, is caused by dense hydrogen at a specific temperature. These two assumptions led to the “black hole” hypothesis.

“Star-like black holes [power] massive black holes surrounded by dense gas,” de Graaff explained. When black holes accrete surrounding matter, they emit a lot of light and therefore heat the gas, causing it to glow and appear like a star.

“The main difference, of course, is that normal stars are powered by nuclear fusion, which doesn't happen here,” de Graaff said. A black hole star can be thought of as a hot object enveloped in a superdense shell.

“The 'black hole-star' hypothesis is certainly intriguing,” said Pacucci. “This work is interesting because it attempts to connect the unexplained observed features of the small red dots with such theoretical ideas.”

Pacucci noted that other small red dots may have similar features to Cliff, which may have gone undetected due to observational limitations. However, the “black hole-star” hypothesis is still in its infancy. Testing the reliability of this scenario will require many more observations, and monitoring these objects dynamically will help differentiate between the scenarios, Pacucci noted.

“We're not yet sure how they evolved into the black hole population we see today,” de Graaff noted. “Because the number of small red dots decreases in later cosmic epochs, this phase must be short-lived.” The team will next use JWST to study brighter small red dots to understand the detailed structure of black hole stars.