Black Hole Collision May Have Caused Massive Gamma-Ray Explosion

What makes the most powerful explosion in the universe? Two black holes merging, of course. A new study published in the journal Monthly Notices of the Royal Astronomical Society researched this phenomenon using short gamma-ray bursts.

In 2012, researchers found evidence that a powerful blast of radiation struck Earth during the Middle Ages, around the 8^th century. The team that conducted the study found that there was an unusual level of a radioactive type of carbon known as carbon-14 in ancient cedar trees in Japan. They found a corresponding spike of radiation levels in Antarctica in the form of beryllium-10 in the ice. The scientists were able to determine the time of the blast through the use of the tree rings in the cedar trees. However, it's only now that the source of this radiation has come to light.

Professor Ralph Neuhauser and his team of German scientists have suggested that the source was a massive explosion in our Milky Way. In order to come to their conclusion, they looked at the spectra of short gamma-ray bursts in order to estimate whether it was consistent with the production of carbon-14 and beryllium-10. They found that they were indeed consistent.

Gamma-ray bursts are produced when black holes, neutron stars, or white dwarfs collide. While the mergers take just seconds, they send out a vast wave of radiation which could impact other planetary bodies in their path- such as Earth.

According to Neuhauser, though, the explosion probably occurred between 3,000 to 12,000 light-years away. At that distance, most of the radiation would have been absorbed by our atmosphere and would have only left a trace in the isotopes that found their way into the trees and ice. It's likely that our ancestors never even took notice of the event.

Previous research suggested that an unusually large solar flare from the sun was to blame for the blast of radiation. This leaves the ultimate cause of the radiation still up for debate.