BLACK holes do not have a reputation for giving up their secrets, but they could prove instrumental in uncovering exotic particles that are difficult to detect on Earth.

If conditions are right, a particle scattering from a spinning black hole will trigger the formation of a new particle. This also causes the black hole to lose a little angular momentum, an effect known as “superradiance”.

Asimina Arvanitaki of the University of California, Berkeley, and colleagues say this loss of angular momentum could be exploited in the hunt for hypothetical particles called axions, which could constitute the invisible cold dark …