Ultra-Light Dark Matter Resonates with Binary Pulsars

Understand

We consider the scenario where dark matter (DM) is represented by an ultra-light classical scalar field performing coherent periodic oscillations.

• We point out that such DM perturbs the dynamics of binary systems either through its gravitational field or via direct coupling to ordinary matter.
• This perturbation gets resonantly amplified if the frequency of DM oscillations is close to a (half-)integer multiple of the orbital frequency of the system and leads to a secular variation of the orbital period.
• We suggest to use binary pulsars as probes of this scenario and estimate their sensitivity.