Rebecca Morelle, a science reporter for BBC World Service writes:
In 2012 researchers found evidence that our planet had been struck by a blast of radiation during the Middle Ages, but there was debate over what kind of cosmic event could have caused this.
Now a study suggests it was the result of two black holes or neutron stars merging in our galaxy.
This collision would have hurled out vast amounts of energy.
[ . . . ]
Last year, a team of researchers found that some ancient cedar trees in Japan had an unusual level of a radioactive type of carbon known as carbon-14.
Not that this has anything to do with the C14 dating of the shroud. But some will want to consider the possibility. And they should.
UPDATE: See the comment from Paulette.