Matter Power Spectrum of Light Freeze-in Dark Matter: With or without Self-Interaction

Abstract

We study the free-streaming effect in a light freeze-in dark matter model. Naturally in the dark sector one can find dark matter related coupling, and such coupling may induce dark matter self-scattering. In case that such scattering is subdominant, the dark matter partition function is not thermal but determined by the freeze-in process, yet its high momentum side is generally also Boltzmann suppressed. We show that the matter power spectrum is very similar to a warm dark matter one in shape. When matched to the current WDM bound, a $24$~keV freeze-in dark matter is ruled out at $2\sigma$ confidence level. In case that the dark matter self-scattering is strong and decouples at a very late time, by a new numerical calculation we show that the early stage Brownian motion indeed protects the power spectrum against free-streaming suppression. However, such an effect cannot be characterized by a free-streaming length alone; we find that the self-scattering decoupling time is another necessary parameter. The currently interested dark matter self-interaction cross section $\sim {\text{cm}}^2/\text{g}$ is just marginal for such protection to be effective.

arXiv comment5 pages, 4 figures. Version published on PLB

References in corpus (22)

• Efficient Computation of CMB anisotropies in closed FRW models
• Observational evidence for self-interacting cold dark matter
• Dark Matter Search Results from a One Tonne$\times$Year Exposure of XENON1T
• Cosmological Perturbation Theory in the Synchronous and Conformal Newtonian Gauges
• Cosmological Perturbation Theory in the Synchronous vs. Conformal Newtonian Gauge
• Dark Matter Self-interactions and Small Scale Structure
• Dark Matter Results From 54-Ton-Day Exposure of PandaX-II Experiment
• New Constraints on the free-streaming of warm dark matter from intermediate and small scale Lyman-$\alpha$ forest data
• The Dawn of FIMP Dark Matter: A Review of Models and Constraints
• Thermally Generated Gauge Singlet Scalars as Self-Interacting Dark Matter
• The Fermi Galactic Center GeV Excess and Implications for Dark Matter
• Light Dark Matter: Models and Constraints
• ETHOS - An Effective Theory of Structure Formation: From dark particle physics to the matter distribution of the Universe
• On Effective Degrees of Freedom in the Early Universe
• Dark Matter Searches at Colliders
• Constraints on Self-Interacting Dark Matter
• Observational rotation curves and density profiles vs. the Thomas-Fermi galaxy structure theory
• E-Wimps
• 7 keV Scalar Dark Matter and the Anomalous Galactic X-ray Spectrum
• Signatures of Self-Interacting Dark Matter in the Matter Power Spectrum and the CMB
• keV Warm Dark Matter via the Supersymmetric Higgs Portal
• Constraining Decaying Dark Matter

Cited by in corpus (16)

• Lower Mass Bounds on FIMP Dark Matter Produced via Freeze-In
• The Higgs Portal to Cosmology
• The cosmology of sub-MeV dark matter freeze-in
• Relativistic Freeze-in
• Neutrino dark matter and the Higgs portal: improved freeze-in analysis
• From WIMPs to FIMPs with Low Reheating Temperatures
• The Cosmological Evolution of Self-interacting Dark Matter
• From WIMPs to FIMPs: Impact of Early Matter Domination
• Dark Stars Powered by Self-Interacting Dark Matter
• Stealth decaying spin-1 dark matter
• Testing freeze-in with axial and vector $Z^{\prime }$ bosons
• Evaluating Lyman-$\alpha$ Constraints for General Dark-Matter Velocity Distributions: Multiple Scales and Cautionary Tales
• Dark matter self-interactions in the matter power spectrum
• Frozen-in fermionic singlet dark matter in non-standard cosmology with a decaying fluid
• Self-Interacting Dark Matter in Cosmology: accurate numerical implementation and observational constraints
• COZMIC. III. Cosmological Zoom-in Simulations of Self-interacting Dark Matter with Suppressed Initial Conditions