Parkes Pulsar Timing Array constraints on ultralight scalar-field dark matter

The existence of ultralight bosonic dark matter with mass of the order of 10⁻²² eV has been proposed to resolve certain observational puzzles. A mechanism identified by Khmelnitsky and Rubakov relates the presence of ultralight dark matter to a time-dependent variation in the times of arrival of radio pulses from pulsars. By searching data collected over more than a decade, the Parkes Pulsar Timing Array collaboration reports new and independent bounds on the density of ultralight bosonic dark matter in the vicinity of Earth.