Pulsar pair ripples spacetime
Duo’s tightening orbits provide even stronger evidence for gravitational waves
By Andrew Grant
GENEVA — A dancing duo of cosmic beacons has provided scientists with the most precise measurement, albeit an indirect one, of ripples in spacetime called gravitational waves.
The measurement comes from analyzing the only known pair of gravitationally bound pulsars, dense cores of dead stars that emit intense beams of radio waves with the regularity of a nearly perfect clock. Michael Kramer, an astrophysicist at the Max Planck Institute for Radio Astronomy in Bonn, Germany, and colleagues precisely tracked the deterioration of the pulsars’ orbits, presumably due to loss of energy in the form of gravitational waves. The rate of orbital wane matches perfectly with the predictions of general relativity, Kramer reported December 16 at the Texas Symposium on Relativistic Astrophysics.