The gravitational wave background
Pulsars across the galaxy reveal spacetime humming from merging supermassive black holes.
- When
- Known to
- ± 12 hours
- Era
- Contemporary, Holocene
On 28 June 2023 pulsar timing array collaborations on four continents announced evidence for a low-frequency gravitational wave background, found by watching millisecond pulsars drift by billionths of a second over fifteen years. The signal is thought to come from pairs of supermassive black holes spiralling together across the universe — a different regime entirely from the single mergers LIGO detects.