
Cosmic Recycling: Heavier Black Holes Form From Repeated Mergers
An analysis of 153 black-hole mergers via gravitational waves reveals two populations: lighter black holes up to ~40 solar masses with spins aligned from stellar collapse, and heavier black holes above ~45 solar masses with chaotic spins, indicating they are second-generation products from prior mergers. This provides evidence that the heaviest black holes are created by repeated collisions in dense stellar environments rather than direct collapse from single stars.






