Dark matter self-interactions in the matter power spectrum

Abstract

We study the imprints of secluded dark sectors with a mass gap and self-interactions on the matter power spectrum. When Dark Matter (DM) is sufficiently light, in the ballpark of a few KeV, and self-interacting we find qualitative difference with respect to $\Lambda$CDM and also to free streaming DM. In order to emphasize the role of interactions for the evolution of the primordial perturbations we discuss various regimes: ranging from the ideal case of a tightly coupled perfect fluid to the free case of Warm Dark Matter, including the realistic case of small but non-vanishing self-interactions. We compute the matter power spectrum in all these regimes with the aid of Boltzmann solvers. Light dark sectors with self-interactions are efficiently constrained by Lyman-$\alpha$ data and we find that the presence of self-interactions relaxes the bound on the DM mass. As a concrete realization we study models with dark QCD-like sectors, where DM is made of light dark-pions.

28 pages, 8 figures. v2) refs added, typos fixed, matches published version

References in corpus (8)

• Can sterile neutrinos be ruled out as warm dark matter candidates?
• Interacting Dark Sector and Precision Cosmology
• Cold keV dark matter from decays and scatterings
• Lyman-$\alpha$ constraints on freeze-in and superWIMPs
• Dark QCD Matters
• Cannibalism's lingering imprint on the matter power spectrum
• Massive Fermi Gas in the Expanding Universe
• Self-Interacting Dark Matter in Cosmology: accurate numerical implementation and observational constraints

Cited by in corpus (2)

• Cannibal dark matter decoupled from standard model: cosmological constraints
• Time-delayed neutrino emission from supernovae as a probe of dark matter-neutrino interactions