Study Finds 14% of 155 Black Hole Mergers Are Second-Generation
Updated
Updated · Gizmodo · Jul 10
Study Finds 14% of 155 Black Hole Mergers Are Second-Generation
1 articles · Updated · Gizmodo · Jul 10
Summary
Researchers analyzing 155 binary black hole mergers detected by LIGO, Virgo and KAGRA estimate about 14% involve black holes formed in earlier mergers.
The team reached that result by modeling orbital precession—the wobble caused when black hole spins are misaligned—which can reveal the masses and spins expected in hierarchical mergers.
Those second-generation candidates cluster around roughly 20 solar masses or 40 solar masses and above, with the latter overlapping a mass gap where standard stellar-collapse theory says black holes should not form.
The pattern points to dense stellar environments as likely breeding grounds for repeated mergers and adds to evidence that some black holes grow through cosmic chain reactions rather than a single star's collapse.
Are cosmic 'chain reactions' creating generations of black holes that defy our old understanding of the universe?
How does a 'wobble' in spacetime prove that some black holes are born from the wreckage of others?
GWTC-5.0 Catalog Unveils Robust Evidence for Second-Generation Black Holes from 161 New Mergers
Overview
Recent breakthroughs in gravitational wave astronomy, highlighted by the expanded GWTC-5.0 catalog, have revealed that some black holes are born from the mergers of other black holes. With 161 new events detected between April 2024 and January 2025, the total number of observed gravitational wave events has reached 390. This larger dataset is crucial for understanding how black holes form. Notably, scientists have identified a subset of binary black hole mergers that show strong evidence for a hierarchical origin, meaning at least one black hole in the pair was itself created by a previous merger, offering new insights into black hole evolution.