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

Understand

It is widely accepted that dark matter contributes about a quarter of the critical mass-energy density in our Universe.

• The nature of dark matter is currently unknown, with the mass of possible constituents spanning nearly one hundred orders of magnitude.
• The ultralight scalar field dark matter, consisting of extremely light bosons with $m \sim 10^{-22}$ eV and often called "fuzzy" dark matter, provides intriguing solutions to some challenges at sub-Galactic scales for the standard cold dark matter model.
• As shown by Khmelnitsky and Rubakov, such a scalar field in the Galaxy would produce an oscillating gravitational potential with nanohertz frequencies, resulting in periodic variations in the times of arrival of radio pulses from pulsars.