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Title: Evidence for dark matter interactions in cosmological precision data?

We study a two-parameter extension of the cosmological standard model ΛCDM in which cold dark matter interacts with a new form of dark radiation. The two parameters correspond to the energy density in the dark radiation fluid ΔN{sub fluid} and the interaction strength between dark matter and dark radiation. The interactions give rise to a very weak ''dark matter drag'' which damps the growth of matter density perturbations throughout radiation domination, allowing to reconcile the tension between predictions of large scale structure from the CMB and direct measurements of σ{sub 8}. We perform a precision fit to Planck CMB data, BAO, large scale structure, and direct measurements of the expansion rate of the universe today. Our model lowers the χ-squared relative to ΛCDM by about 12, corresponding to a preference for non-zero dark matter drag by more than 3σ. Particle physics models which naturally produce a dark matter drag of the required form include the recently proposed non-Abelian dark matter model in which the dark radiation corresponds to massless dark gluons.
Authors:
 [1] ; ;  [2]
  1. Institut für Theoretische Teilchenphysik und Kosmologie (TTK), RWTH Aachen University, Aachen, 52056 Germany (Germany)
  2. Physics Department, Boston University, Boston, MA, 02215 (United States)
Publication Date:
OSTI Identifier:
22524999
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2016; Journal Issue: 02; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCURACY; COSMOLOGICAL CONSTANT; COSMOLOGICAL MODELS; COSMOLOGY; DENSITY; DISTURBANCES; ENERGY DENSITY; FLUIDS; GLUONS; NONLUMINOUS MATTER; STANDARD MODEL; UNIVERSE