Black hole mergers put limits on star-destroying supernovae

Pair-instability in very massive stars can trigger rapid oxygen fusion that may fully disrupt the star or strip its envelope.

Weaker oxygen bursts can leave smaller stellar remnants that form lower-mass black holes later.

Researchers modeled merger types—G1-G1, G1-G2, G2-G2—and note that many large black holes could be second-generation products.

They estimate G2-G2 mergers are rare, about 1% of all mergers, because merger recoil can eject remnants from clusters.