January 21, 2013
Earth Was Blasted With A Gamma Ray Burst During The Eighth Century
Lee Rannals for redOrbit.com - Your Universe Online
According to a new study, black hole cosmic radiation blasted into the Earth back in the 8th century.
Japanese astrophysicist Fusa Miyake discovered last year clues for the strange event located in the rings of ancient cedar trees that dated back to either 774 or 775 AD.
Researchers teamed together to determine what had caused the surge in carbon-14 in the rings and found no evidence of a supernova, as they had expected.
The Anglo-Saxon Chronicle references the appearance of a "red crucifix" seen in the skies after sunset, but that took place in 776 AD, which was too late for when the tree rings show the event took place.
Scientists were also able to rule out a CME burst from the Sun, during which solar flares shoot out cosmic rays, sometimes towards Earth.
They wrote in the Monthly Notices of the Royal Astronomical Society, instead, black holes may be the culprit behind the carbon-14 isotope surge in the rings. These isotopes are created when intense radiation hits the atoms in the upper atmosphere, which suggests a blast of energy had once hit Earth.
German-based scientists Valeri Hambaryan and Ralph Neuhauser say two black holes collided and then merged, releasing an intense, but extremely brief, burst of gamma rays during the time period. The same kind of bursts could have also taken place if two neutron stars, or white dwarf stars, collided.
"Gamma-ray bursts are very, very explosive and energetic events, and so we considered from the energy what would be the distance given the energy observed," Neuhauser wrote in the journal.
They said the event could only have taken place at least 3,000 light years away from here, otherwise the planet would have been fried.
Also, if their theory is right, then it would help explain why there is no record of some brilliant event taking place in the sky, or evidence of any extinction event in Earth's biodiversity during the time.
The authors suggest astronomers should look up to the sky for any evidence that may still exist today from the astronomical event in 774 or 775 AD.
Neuhauser said if a gamma-ray burst had been much closer to earth, then it would have caused significant harm to the biosphere.
"But even thousands of light years away, a similar event today could cause havoc with the sensitive electronic systems that advanced societies have come to depend on," he wrote in the journal. "The challenge now is to establish how rare such carbon-14 spikes are, i.e. how often such radiation bursts hit the Earth."
He said in the last 3,000 years, the maximum age of trees alive today, only one of these events has taken place. He added it was unlikely Earth would be seeing another one of these cosmic events soon.