Researchers weigh primordial black holes as little red dot explanation

Vasily Kokorev of the University of Texas at Austin led a team that published the most detailed spectrum ever taken of a little red dot on June 10, 2026, in The Astrophysical Journal.

Simulations on Japan’s ATERUI III supercomputer indicate JWST’s Little Red Dots are fast-growing black holes from the early Universe. Sunmyon Chon of the Max Planck Institute for Astrophysics led the research team using ATERUI III. The work required the high-performance computing capacity of ATERUI III for detailed early-Universe cosmological simulations.

Johns Hopkins researchers examined whether QSO1, one little red dot seen by the James Webb Space Telescope, might hold a primordial black hole – a black hole formed in the early universe before the first stars – that existed before stars and heavier elements. QSO1 existed when the universe was only 700 million years old and consists nearly entirely of hydrogen and helium, without heavier elements. Researchers suspected QSO1 might contain a primordial black hole because of its age, size and makeup.

Little red dots are compact red objects first spotted in James Webb Space Telescope images in 2022. Astronomer Jorryt Matthee and colleagues formally named them in a March 2024 study. They look blue in ultraviolet light and red in optical light, with broad hydrogen lines showing fast-moving gas.

The objects appear in large numbers starting 600 million years after the universe began and vanish by about 1.6 billion years after the universe began. By 2025, researchers had catalogued 341 little red dots.

The abundance and apparent masses of little red dots seemed to challenge standard models of cosmic structure formation. Early calculations suggested far more early supermassive black holes than standard cosmology predicts. JWST started science operations in July 2022, and little red dots appeared in nearly every image, leading some researchers to claim the telescope had broken cosmology.

Astronomers have long struggled to explain how supermassive black holes containing millions or billions of solar masses existed less than 600 million years after the universe began. Some of these black holes hold millions or billions of solar masses despite appearing under 600 million years after the universe began.

A January 2026 Nature study by Rusakov and colleagues, based on 12 objects, found black holes within little red dots are likely 100 times less massive than prior estimates. Electron scattering in dense gas cocoons makes little red dot black holes appear more massive than they are; once corrected, the Rusakov team found masses from 100,000 to 10 million solar masses. The corrected masses fit standard models of black hole growth in the early universe. The mass correction removes most of the apparent surplus that disturbed cosmologists.

Valerio De Luca, a Johns Hopkins postdoctoral researcher in physics and astronomy, said primordial black holes arise from early-universe physics before the first stars during exponential expansion. De Luca said if primordial black holes exist, some process must have created them after the Big Bang, which would represent a major advance in physics. De Luca said creating primordial black holes after the Big Bang would require a new physical process and would be a major discovery.

Loris Del Grosso, a Johns Hopkins postdoctoral researcher in physics and astronomy, said cosmological observations limit how many primordial black holes can exist and how many can occupy one cluster. De Luca and Del Grosso said proving primordial black holes exist requires finding one either lighter than any astrophysical black hole or older than the first stars. A definitive detection would require finding an unusually lightweight or ancient black hole.

De Luca said, “They come from the physics of the early universe that predates the first stars, when the universe was expanding exponentially in time and space.” The Johns Hopkins researchers are searching for the first black holes, and the work could reveal how primordial black holes, for which scientists lack direct evidence, might form.

Johns Hopkins researchers modeled three scenarios to test if a primordial black hole could grow into a little red dot the size of QSO1 surrounded by many disks, using QSO1 as a test case for the idea. The leading scenario has a smaller primordial black hole pulling in and consuming nearby gas and energy until it reaches QSO1’s size. The Johns Hopkins team intends to check how many of the 100 little red dots already observed and cataloged could be primordial black holes, and the next step is to survey the cataloged population for similar objects.

The Johns Hopkins findings appear in Physical Review Letters under the title Primordial-Black-Hole-Based Pathways to Little Red Dots by Valerio De Luca et al., with DOI 10.1103/6y1w-87pd. The paper lists Valerio De Luca as first author and gives the journal article identifier. Since Stephen Hawking proposed primordial black holes in the 1970s, scientists have sought proof of their existence and a way to tell them apart from astrophysical black holes.

Strong far-ultraviolet radiation from neighboring galaxies can stop normal stars from forming in some gas clouds, so the gas collapses into one supermassive star that then forms a black hole seed. Rather than fragmenting into many small stars, the gas forms a single massive star under the radiation.

Dense gas disks around the black hole seeds trap radiation and let the black holes eat matter far more efficiently than in the modern cosmos, and the gas-rich surroundings capture radiation and permit efficient feeding. In early-universe conditions, the simulated black holes can grow at rates dozens of times higher than in the modern cosmos because the early environment differs from the modern cosmos.

The simulated black holes closely match the Little Red Dots that the James Webb Space Telescope observed. The similarity implies little red dots might be an early phase of rapid black hole growth. The National Institutes of Natural Sciences says the conditions to make and quickly grow these black holes arose naturally in the early Universe without exotic assumptions. The model does not rely on exotic physics or improbable events.

Kokorev’s spectrum observed GLIMPSE-17775, a little red dot at cosmological redshift – a measure of how much light has stretched as the universe expanded – of 3.5, whose light left roughly 1.8 billion years after the cosmos began. JWST aimed at galaxy cluster Abell S1063 for the GLIMPSE program run by Hakim Atek of the Institut d’Astrophysique de Paris when it observed GLIMPSE-17775. GLIMPSE is a survey meant to find Population III stars, the first generation of stars, and faint early galaxies. GLIMPSE-17775 lay behind Abell S1063.

Gravity from Abell S1063 bent and magnified GLIMPSE-17775’s light, turning 30 hours of JWST observing into an effective exposure of about 80 hours. No earlier little red dot received so much observing time. Kokorev said earlier little red dot spectra lacked all the evidence together in one place. The spectrum has more than 40 spectral lines, setting a new detail record for light from a little red dot.

The black hole star model places a supermassive black hole consuming gas at an extreme rate likely above the Eddington limit – the maximum rate at which an object can emit light while pulling in matter. The central engine gives off intense X-rays and ultraviolet light. A thick cocoon of partially ionized gas around the black hole absorbs energetic photons and re-emits the energy at longer, redder wavelengths. The gas layer is thick enough to trap most high-energy photons before they escape.

This process accounts for the red color, weak X-ray output, and broad spectral lines seen in little red dots. A dense hot gas shield converts the blue and X-ray radiation into cooler light. The broad lines result from electron scattering in a dense gas layer rather than from gas orbiting the black hole. The line shape reveals the gas column density and geometry rather than only its speed.

GLIMPSE-17775’s spectrum includes an iron forest of overlapping emission lines from singly ionized iron, helium absorption features, and fluorescence signatures needing strong ultraviolet light. These features are multiple independent indicators pointing to the same conclusion.

Kokorev said viewing the GLIMPSE-17775 spectrum resembled having every piece of a puzzle scattered across the floor. Kokorev made the remark in a statement released with the paper.

Kokorev said other interesting theories exist and the field anticipates a clear answer within one or two years about the power source of these objects, adding that alternatives remain and the answer should arrive within a year or two. The supermassive primordial star hypothesis cannot be excluded for the full little red dot population based on one object alone, because a single object cannot settle the question for every little red dot. In January 2026, researchers at the Harvard-Smithsonian Center for Astrophysics suggested some little red dots might be supermassive primordial stars just before collapsing into black holes, and the Harvard-Smithsonian proposal is one of three major explanations circulating by early 2026.

Future JWST programs targeting lensed little red dots will either uncover the same supporting evidence across the class or find true exceptions needing another explanation. Researchers can repeat the lensing trick for any other little red dot behind a massive galaxy cluster. Early JWST observations of little red dots prompted claims that the telescope had broken cosmology, but corrected mass estimates suggest the objects fit standard models of black hole growth instead.