The Universe Sings: Resonance of Dark and Ordinary Matter ⚡ экспресс

After decoupling in the early Universe, dark matter and baryons acquire a relative velocity. It is shown that their drift triggers a resonant gravitational instability: when dark matter moves subsonically, stable baryon oscillations resonate with the Doppler-shifted dark matter mode, leading to exponential growth of perturbations at a rate exceeding that of cold dark matter alone. The instability is strongest on scales smaller than the baryonic Jeans length; in baryon-dominated environments, a stability window appears between the Jeans scale and the resonance. Supersonic drift suppresses growth. An analytic approximation gives resonant growth rates with characteristic timescales from years to tens of millions of years—from planets to galaxy clusters—much shorter than their ages. In an expanding FLRW universe, the instability amplifies baryonic perturbations on some modes and suppresses them on others. This resonant mechanism offers a new way to probe dark matter through seismic imprints and may explain the persistence of spiral arms and the heating of the intracluster medium.