Charismatic Megaparticles Might Hint at Dark Matter, and Much Besides

At a lecture I went to some years ago, astrophysicist Trevor Weekes compared garden-variety elementary particles to mosquitoes. They are plentiful and easy to find indeed, they find you. But ultra-high-energy gamma rays, he said, are like elephants. They are fairly rare, but among the greatest of creatures. They often roam in spectacular habitats. Their sheer heft tests the limits of the laws of nature.I naturally wanted to invite an article for Sci Am about these charismatic megaparticles, but for years I struggled with what the article would say. Although they may be the most powerful electromagnetic radiation known to science photons with an energy of around a teraelectron-volts (TeV), the kinetic energy of a mosquito concentrated into a single quantum once you use up all the superlatives in your thesaurus, what was there to say, really? At the time I saw Weekes speak, astronomers had found a grand total of about a dozen celestial sources of TeV gamma rays, and they were the usual suspects: giant black holes and suchlike. Teragammas had revealed nothing about the ecology of the universe which astronomers didn’t already know. They were like animals in a zoo rather than out in the wild: fun ...