The news last month that gravitational waves had been discovered made waves throughout the world of science. The finding, from the Laser Interferometer Gravitational-Wave Observatory, or LIGO, showed that extreme gravity can cause ripples in spacetime. In the case studied, the extreme gravity came from two colliding black holes. Now one scientist is suggesting an added wrinkle—that those two black holes might have originated in a single star.
“The situation is similar to a pregnant woman that has twin babies in her belly.” Avi Loeb of the Harvard-Smithsonian Center for Astrophysics. He’s proposing the idea in a paper that’s been accepted for publication in the Astrophysical Journal Letters. [Abraham Loeb, Electromagnetic Counterparts to Black Hole Mergers Detected by LIGO]
Loeb became suspicious because just 0.4 seconds after LIGO spotted the gravitational waves, a space telescope called Fermi glimpsed a bright flash of gamma-ray light in the same area of the sky.
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“Detecting such a signal is quite surprising from a collision of two black holes. What could be the source of a flash of light following a black hole merger?”
Colliding black holes should not produce such light—but the death of a very massive star could.
“My idea was that if the star is spinning very rapidly to start with, then as its core collapses it produces a bar that breaks into two clumps of matter, sort of like a dumbbell configuration. And these two clumps of matter orbit a common center, and they eventually collapse independently into two black holes.”
Of course, it’s possible that the Fermi telescope signal was a false alarm. So we’ll see if future gravitational wave detections are also accompanied by flashes of light—supporting the idea that twin black holes collided upon the collapse of a massive star.
—Clara Moskowitz
[The above text is a transcript of this podcast.]
