Almost all the 'missing' dark matter in the universe could just be ancient black holes hiding in massive, invisible clusters.
March 25, 2026
Original Paper
Microlensing by Cluster of Primordial Black Holes
arXiv · 2603.23412
The Takeaway
Scientists have spent decades looking for individual black holes to explain dark matter, but found very few. This research shows that if these black holes travel in tight-knit 'packs' or clusters, they would be almost impossible for our current telescopes to detect, hiding up to 93% of the dark matter population.
From the abstract
Numerous microlensing survey programs have constrained the possibility of dark matter existing in the form of compact objects within the Galactic halo. These constraints on the dark matter fraction were derived under the assumption of isolated, widely separated objects. This work investigates microlensing by primordial black holes (PBHs) organized into clusters. In this scenario, it is necessary to account for both the influence of neighboring PBHs and the collective gravitational potential of t