Did a Gamma Ray Burst Accompany LIGO’s Gravity Wave Detection?

An artist's impression of a Gamma Ray Burst. Credit: Stanford.edu

Last week’s announcement that Gravitational Waves (GW) have been detected for the first time—as a result of the merger of two black holes—is huge news. But now a Gamma Ray Burst (GRB) originating from the same place, and that arrived at Earth 0.4 seconds after the GW, is making news. Isolated black holes aren’t supposed to create GRB’s; they need to be near a large amount of matter to do that.NASA’s Fermi telescope detected the GRB, coming from the same point as the GW, a mere 0.4 seconds after the waves arrived. Though we can’t be absolutely certain that the two phenomena are from the same black hole merger, the Fermi team calculates the odds of that being a coincidence at only 0.0022%. That’s a pretty solid correlation.So what’s going on here? To back up a little, let’s look at what we thought was happening when LIGO detected gravitational waves.Our understanding was that the two black holes orbited each other for a long time. As they did so, their massive gravity would have cleared the area around them of matter. By they time they finished circling each other and merged, they would have been isolated in space. But now that a GRB has been detected, we need some way to account for it. We need more matter to be present.According to Abraham Loeb, of Harvard University, the missing piece of this puzzle is a massive star—itself the result of a binary star system combining into one—a few hundred times larger than the Sun, that spawned two black holes. A star this size would form a black hole when it exhausted its fuel and collapsed. But why would there be two black holes?Again, according to Loeb, if the star was rotating at a high enough rate—just below its break up frequency—the —> Read More