Weird high-energy flare made by spitting black hole

GLOBS of plasma spat out by black holes can trigger the brightest flashes of light in the universe.

Gamma-ray bursts are high-energy flares that mostly originate billions of light years away, making it hard to see how they are created. In November 2011, NASA’s Fermi satellite saw a gamma-ray burst coming from the galaxy 4C +71.07, which sits about 10.5 billion light years away. The galaxy was also being watched by the Very Long Baseline Array, a radio telescope network that can see small features at a distance.

The supermassive black hole at the galaxy’s centre is feeding on surrounding matter, causing it to fire high-speed jets of particles. The radio array showed that, around the same time as the flare, the black hole spat out a knot of plasma that travelled up the jet at near the speed of light.

Electrons in the knot probably collided with and energised light from a slower-moving part of the jet, producing the gamma rays, says Alan Marscher of Boston University, who presented the work at a recent astronomy meeting in California. It’s still a mystery, though, what made the black hole erupt.