Gravitational Waves Illuminate Neutron Star Collisions
Four times in the past 2 years, physicists working with mammoth gravitational-wave detectors have sensed something go bump in the night, sending invisible ripples through spacetime. Today, they announced the detection of a fifth such disturbance—but this time astronomers saw it, too, at every wavelength of light from gamma radiation to radio waves. Just as physicists had predicted, the unprecedented view of the cosmic cataclysm—in which two superdense neutron stars spiraled into each other—brought with it a cornucopia of insights, each of which by itself would count as a major scientific advance.
“It’s really a big gift that nature has given us,” says Alessandra Corsi, a radio astronomer at Texas Tech University in Lubbock. “It’s a life-changing event.”
At 12:41 universal time on 17 August, physicists with three massive instruments—the twin 8-kilometer-long detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) in Hanford, Washington, and Livingston, Louisiana, and the 6-kilometer Virgo detector near Pisa, Italy—spotted waves unlike any seen before. The four previous events lasted for, at most, a few seconds, with gravitational waves rippling at frequencies of tens of cycles per second. The new siren sang for 100 seconds at frequencies climbing to thousands of cycles per second. Whereas the earlier signal came from pairs of huge black holes quickly spiraling into each other, the new signal revealed lighter neutron stars, 1.1 and 1.6 times as massive as the sun, twirling inexorably together, researchers announced in parallel press conferences in Washington, D.C., and Garching, Germany.