WIMPs wipe each other out in giant radiating spot at galaxy's centre

What's 10,000 light years across and smells of gamma radiation? Weakly interacting massive particles - WIMPs, one of the candidate hypotheses to explain dark matter - are so hard to find on Earth that nobody's ever seen them. However, a just-released analysis of years of gamma ray data suggests they're at the centre of the Milky Way in enormous numbers....