Gravitational‑wave catalog GWTC-4 doubles the event tally to 128
The LVK collaboration’s GWTC-4 catalog adds 128 distant gravitational‑wave sources detected from 2023–2024, expanding beyond the previous 90; the data include heavier, faster black‑hole mergers, some lopsided in mass, and two mixed black hole–neutron star mergers, with detections up to 10 billion light‑years away, underscoring general relativity under extreme conditions and expanding our view of black‑hole populations.