Dark signs from Centaurus A (Image: NASA/CXC/SAO/M.Karovska et al)

TWO of the darkest things in the universe may be making light – or at least, radiation. When jets spat out by a supermassive black hole at the centre of a galaxy collide with dark matter, they could produce gamma rays detectable from Earth – possible evidence of the elusive dark stuff.

Jets of particles are propelled away from black holes at near the speed of light. Akin to a cosmic belch, they are thought to be connected with matter falling into the black hole. Stefano Profumo of the University of California, …