The James Webb Space Telescope (JWST) has deepened a major cosmic mystery by revealing that supermassive black holes (SMBHs) with masses of billions of suns existed less than a billion years after the Big Bang. This poses a challenge to conventional models, which propose that SMBHs grow gradually over time through mergers and accretion of material. With only a few hundred million years available, these black holes seem to have grown far too quickly.

To solve this, a new study led by Francesco Ziparo of the Scuola Normale Superiore di Pisa proposes a novel approach: primordial black holes (PBHs) as seeds for early SMBHs. PBHs, unlike stellar black holes, would have formed directly from dense regions of subatomic matter shortly after the Big Bang, allowing them to bypass the slower growth processes tied to stellar-mass black holes. In the team’s model, PBHs around 30 times the Sun’s mass would cluster in dense regions where dark matter halos—structures that help galaxies form—were emerging. Over time, these PBHs would lose angular momentum due to gas friction, concentrate at the centers of these halos, and undergo rapid mergers, forming larger black hole seeds that could grow into SMBHs within the short timescale JWST has observed.

To test this model, the researchers propose using future gravitational wave detectors, like the planned Einstein Telescope. During the rapid merger phase, PBHs would emit strong gravitational waves, which the Einstein Telescope’s sensitivity could potentially detect. This would offer a new method for investigating the existence of PBHs and their role as SMBH seeds.

If validated, this model could transform our understanding of how black holes and the universe’s large-scale structures developed in the early cosmos. Since SMBHs influence galaxy formation and the distribution of matter, unraveling their origins might reveal fundamental insights into the evolution of the universe itself.