Astronomers have proposed that an unusually large black hole in a galaxy from 13 billion years ago could be a primordial remnant from the universe's dawn. Spotted by the James Webb Space Telescope, the black hole is 50 million times the sun's mass but lacks surrounding stars, challenging traditional formation theories. Detailed simulations indicate it may have originated from density fluctuations after the big bang.
In August, researchers led by Boyuan Liu at the University of Cambridge detected the galaxy Abell 2744-QSO1 using the James Webb Space Telescope (JWST). This distant galaxy, dating back 13 billion years, hosts a black hole approximately 50 million times the mass of the sun, yet it appears almost entirely devoid of stars.
Liu noted the anomaly: “This is a puzzle, because the traditional theory says that you form stars first, or together with black holes.” Conventionally, black holes form from the collapse of massive stars that have exhausted their fuel.
To explain this, Liu's team explored the concept of primordial black holes, first theorized by Stephen Hawking and Bernard Carr in 1974. These hypothetical objects would have formed directly from fluctuations in the universe's density shortly after the big bang, without involving stars.
Initial simple simulations suggested this possibility, but the team conducted more advanced models accounting for gas dynamics, star formation, and interactions around an initial small primordial black hole. Over the universe's first hundreds of millions of years, these simulations predicted growth matching the observed mass of the black hole in QSO1, as well as the presence of heavier elements.
Liu described the findings: “It’s not decisive, but it’s an interesting and a kind of important possibility.” Roberto Maiolino, also at the University of Cambridge and part of the discovery team, added: “The fact that they manage to match the properties of QSO1, both in terms of the black hole mass, the stellar mass and the chemical enrichment, is very interesting and encouraging.”
Challenges remain. Standard simulations produce primordial black holes up to about 1 million solar masses, far smaller than QSO1's. However, clustering could enable rapid mergers to achieve greater size. Additionally, formation might require a nearby high-energy event like a supernova, but none is evident near QSO1.
The work, detailed in arXiv DOI: 10.48550/arXiv.2512.14066, highlights how JWST observations are pushing theories of early universe black holes.