Two merging neutron stars, as illustrated here, do spiral in and emit gravitational waves, but are much more difficult to detect than black holes. However, they should have optical counterparts, which could lead to the first correlation between the gravitational and electromagnetic sky. Image credit: Dana Berry / Skyworks Digital, Inc.

Beyond Black Holes: Could LIGO Have Detected Merging Neutron Stars For The First Time?

For the first time, the gravitational wave sky and the astronomical sky might be coming together. It’s a new era, at long last.

“Presently thought to be the most powerful explosions in nature… their sources have only recently been localized by observations of associated afterglows in X-rays, visible light, and radio waves, delayed in that order.”
-Richard Matzner, on the dictionary entry for Gamma Ray Burst

LIGO, the Laser Interferometer Gravitational-wave Observatory, achieved one of the holy grails of physics: by directly detecting gravitational waves for the first time. This was not an isolated event, either, but the first in a class of events that LIGO has been continuing to expose. During its time of operation, LIGO has seen three significant signals that correspond to the mergers of massive, binary black holes. Each one resulted in the emission of gravitational waves so significant, they compressed-and-rarefied the twin interferometers on Earth by enough to detect these sources from over a billion light years away. Now, scientists are confronting the possibility that LIGO, now joined by VIRGO, may have crossed into the next frontier of gravitational wave phenomena: neutron star…