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SALT LAKE CITY — Radiation found in tree rings may have been the result of two merging black holes during the Middle Ages, a new study says.
Researchers from the Institute of Astrophysics at the University of Jena found in their study that two black holes or neutron stars in the Milky Way likely collided, leaving traces of radiation in trees and ice.
A 2012 study found evidence that a burst of radiation had struck Earth during the Middle Ages.
Researchers based this conclusion on evidence gathered from ancient cedar trees in Japan containing a high level of radiocarbon, carbon-14.
Using tree rings and carbon measurements, they found the radiation occurred between AD 774 and AD 775 and the radiation came from 3,000 and 12,000 light years from the Sun.
The German researchers said their gamma-ray burst theory is consistent with the variables involved with the radiation found in the tree rings because a short gamma-ray burst would provide necessary energy to produce carbon-14. Also, there is no historic sighting of a supernova consistent with the date provided by tree rings. Finally, it was distanced enough from the Earth that no extinction here would have occurred.
They said people on Earth at the time would probably not have noticed, as there likely was no visible light from the burst and the radiation would have been absorbed by the Earth's atmosphere, leaving only a trace in the isotopes.