Gamma Ray Dragons

Highly energetic photons known as gamma rays arrive at the earth from all directions, some of them carrying so much energy we can only guess at the titanic processes that gave birth to them. For a long time the leading guess has been that super energetic gamma rays are produced by giant black holes. As matter spirals into a black hole, it produces (we think) jets of plasma that shoot away at nearly the speed of light, and the interaction between these jets and gas clouds could (we suspect) produce gamma rays. Now NASA's Spitzer gamma ray telescope has produced a gamma ray map of the cosmos (above), allowing us to compare the origin of gamma rays with the locations of giant black holes. It seems that, at most, 30% of the gamma rays reaching the earth might have originated at black holes, and it might be none at all.

Not knowing what else to do, the scientists have named the unknown sources of most gamma radiation "dragons."