Gamma-ray bursts

Gamma-ray bursts are the most violent events in the Universe: During the death of a massive star, its core collapses into a black hole, generating energies so huge they defy adjectival description. This energy is focused into twin beams that drill out from the star and march across space, cosmic blowtorches so luminous they can be seen clear across the Universe. On April 27, 2013, the light from just such a burst reached Earth. It was from the relatively nearby distance of 3.6 billion light years—though still a quarter of the way across the cosmos—so it appeared incredibly bright to our orbiting observatories like Fermi, which took the image above. Gamma rays are the highest energy form of light, and this GRB spewed them out at such a rate that at its peak 100,000 of them were seen every second by the Swift satellite. One of these gamma rays was the highest-energy photon ever seen from a GRB, with an energy 35 billion times that of a photon of visible light. This burst also lasted for hours, allowing many ground-based telescopes to observe it as well.

Photo by NASA/DOE/Fermi LAT Collaboration