Ancient black holes from a pre-Big Bang bounce could account for dark matter

A team led by Enrique Gaztañaga has introduced a bouncing-cosmology model in which the universe transitioned from a dense contracting state to the current expansion, avoiding a singularity. In this scenario, black holes created during the contraction could have passed through the bounce and survived to the present, acting as "cosmic fossils" that influence galaxy formation. The authors argue that a sufficient population of these primordial black holes could explain the majority of dark matter and shed light on why massive structures appeared early in cosmic history.

The bounce mechanism may also address puzzles related to inflation and the universe's current accelerated expansion attributed to dark energy. The study outlines potential observational tests, including searches for relic gravitational waves and faint imprints in the cosmic microwave background. Validation of the model could reshape our understanding of the universe's origin and the nature of dark matter.