Pulsars as detectors for gravitational waves

The nanohertz region of the gravitational wave spectrum is expected to be home to some of the most exotic sources in the Universe. Supermassive black hole binaries at the centres of merging galaxies, cosmic strings and certain forms of dark matter may radiate at these frequencies. Decades-long projects, using radio telescopes around the world to measure the effect of these waves on spinning neutron stars (pulsars), are now seeing the first evidence for a corresponding gravitational wave background.