Challenging the Stability of Light Millicharged Dark Matter

Understand

We investigate the cosmological stability of light bosonic dark matter carrying a tiny electric charge.

• In the wave-like regime of high occupation numbers, annihilation into gauge bosons can be drastically enhanced by parametric resonance.
• The millicharged particle can either be minimally coupled to photons or its electromagnetic interaction can be mediated via kinetic mixing with a massless hidden photon.
• In the case of a direct coupling current observational constraints on the millicharge are stronger than those arising from parametric resonance.