London: A possible source of ultra high-energy cosmic rays – gamma-ray bursts, has received a new lease of life in a new study.
Till now, the gamma-ray bursts, which are usually created by exploding stars that produce neutrinos, seemed to have been ruled out.
So last April, when the IceCube neutrino detector in Antarctica saw no neutrinos accompanying high-energy cosmic rays, astronomers favoured galaxies with active supermassive black holes at their cores as the source of the rays.
However, a more recent study found that only one galaxy was powerful enough to have produced cosmic rays with such high energies, and the rest appear to come from galaxies that seem too weak.
Glennys Farrar of New York University, one of the study authors, said that this posed a “perplexing problem”, New Scientist reported.
They then found a clue in the gamma-ray burst GRB110328A, which happened in March 2011.
Its afterglow continued for over a week, instead of a few hours like normal ones.
The reason was most likely a star falling into a galaxy’s central black hole.
Farrar suggests that this would make a weak black hole flare up, producing a burst of gamma rays that in turn spits out cosmic rays.
The trouble is testing the hypothesis as gamma rays travel at the speed of light and so would arrive millennia ahead of any cosmic rays.