Scientists finally have an explanation for the most energetic explosions in the universe

The brightest explosions in the universe could be the work of ancient, dying stars.

Gamma-ray bursts (GRBs) are the brightest, most energetic blasts of light in the universe. Released by an immense cosmic explosion, a single GRB is capable of shining about a million trillion times brighter than Earth's sun, according to NASA — and, for the most part, scientists can't explain why they happen. Part of the problem is that all known GRBs come from very, very far away — usually billions of light-years from Earth. Sometimes, a GRB's home galaxy is so far-flung that the burst's light appears to come from nowhere at all, briefly blipping out of the black, empty sky and vanishing seconds later. These "empty-sky" gamma-ray bursts, as some astronomers call them, have presented an ongoing cosmic mystery for more than 60 years. But now, a new study, published Sept. 15 in the journal Nature, offers a compelling mathematical explanation for the powerful bursts' origins.

According to the study researchers — who modeled the interactions between gamma rays and other powerful energy sources, such as cosmic rays — all those nebulous empty-sky bursts could be the results of massive stellar explosions in the disks of distant galaxies. "We modeled the gamma-ray emission from all the galaxies in the universe … and found that it is star-forming galaxies that produce the majority of [empty-sky] gamma-ray radiation," lead study author Matt Roth, an astrophysicist at Australian National University in Canberra, said in a statement. Read more...

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