Atomic dark matter

Abstract

We propose that dark matter is dominantly comprised of atomic bound states. We build a simple model and map the parameter space that results in the early universeformation of hydrogen-like dark atoms. We find that atomic dark matter has interestingimplications for cosmology as well as direct detection: Weak-scale dark atoms can accommodate hyperfine splittings of order100 keV, consistent with the inelastic dark matter interpretation ofthe DAMA data while naturally evading direct detectionbounds. Moreover, protohaloformation can be suppressed below Mproto ∼ 103–106M⊙ for weakscale dark matter due to Ion-Radiation and Ion-Atom interactions in the darksector.