How do the biggest black holes in the universe form? Ripples in spacetime provide a clue - Space

1. How do the biggest black holes in the universe form? Ripples in spacetime provide a clue  Space
2. These monster black holes did not form the usual way—their history of violence is written into spacetime ripples  Phys.org
3. Study links biggest black holes to repeated cosmic collisions  Courthouse News
4. Evidence for a 'forbidden range' of black hole masses emerges in gravitational wave observations  Physics World
5. Largest black holes formed by violent mergers, rather than collapsing stars  Innovation News Network