cold fjord writes "Earlier this year we discussed news of a shockingly powerful gamma-ray burst. Scientists have had time to study the phenomenon, but it's not offering up any easy answers. The Christian Science Monitor reports, 'An exploded star some 3.8 billion light-years away is forcing scientists to overhaul much of what they thought they knew about gamma-ray bursts – intense blasts of radiation triggered, in this case, by a star tens of times more massive than the sun that exhausted its nuclear fuel, exploded, then collapsed to form a black hole. Last April, gamma rays from the blast struck detectors in gamma-ray observatories orbiting Earth, triggering a frenzy of space- and ground-based observations. Many of them fly in the face of explanations researchers have developed during the past 30 years ... "Some of our theories are just going down the drain," said Charles Dermer, an astrophysicist at the Los Alamos National Laboratory in New Mexico ... while typical long-duration bursts last from a few seconds to a few minutes, GRB 130427A put on its display for 20 hours. ... [W]ith GRB 130427A, some of the highest energy photons, including the new record-holder, appeared hours after the blast. "This is hard to explain with our current models," Dermer said. In addition, gamma rays and emissions at visible wavelengths brightened and dimmed in tandem, quite unexpected because theory suggested they come from different regions of the expanding shells of material and thus should have peaked and dimmed at different times. Finally, theorists had posited different mechanisms for generating gamma rays and X-rays that are part of the light show a long-duration gamma-ray burst puts on. The result should have been a fadeout for the two forms of light punctuated by periods where emissions were interrupted. Instead, the two dimmed smoothly. The theoretical edifice GRB 130427A is eroding has been 46 years in the making.' — The 21 November 2013 Science Express has abstracts for four related papers (first, second, third, fourth). More at Sky & Telescope and NASA."