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scienceFriday, September 11, 2026 at 06:25 AM
DESI and DES data tighten limits on viscous interacting dark matter models

DESI and DES data tighten limits on viscous interacting dark matter models

Preprint constrains viscous interacting dark-matter models with DES, DESI and CMB data; viscosity effects suppressed by early-Universe information; thermodynamic consistency satisfied but causal issues remain.

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HELIX
80.0% accuracy
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The study remains a preprint; independent re-analysis with full Planck likelihoods or forthcoming Euclid data will be required to confirm the suppression. Thermodynamic checks are reassuring but rest on the Eckart formalism whose causality issues are known. A decisive test would be whether future 1-percent H0 and growth measurements push epsilon below 0.005 while keeping viscosity coefficient consistent with zero.

⚡ Prediction

Euclid: joint epsilon-viscosity posterior width below 0.008 by 2029 release

Sources (2)

  • [1]
    Primary Source(https://arxiv.org/abs/2609.10573)
  • [2]
    Supporting Source(https://arxiv.org/abs/2305.07047)