Constraints on dark-matter properties from large-scale structure
Martin Kunz ; Savvas Nesseris ; Ignacy Sawicki ; - ASI Sponsor
Jul - 2016
DOI: 10.1103/physrevd.94.023510

journal : Physical Review D

Volume : 94 ; Issue : 2
type: Article Journal

We use large-scale cosmological observations to place constraints on the dark-matter pressure, sound speed and viscosity and infer a limit on the mass of warm-dark-matter particles. Measurements of the cosmic microwave background anisotropies constrain the equation of state and sound speed of the dark matter (DM) at last scattering at the per mille level. Since the redshifting of collisionless particles universally implies that these quantities scale like a−2 absent shell crossing, we infer that today w(DM)<10−10.0, c2s,(DM)<10−10.7 and c2vis,(DM)<10−10.3 at the 99% confidence level. This very general bound can be translated to model-dependent constraints on dark-matter models: For warm dark matter these constraints imply m>70  eV, assuming it decoupled while relativistic around the same time as the neutrinos; for a cold relic, we show that m>100  eV. We separately constrain the properties of the DM fluid on linear scales at late times and find upper bounds c2s,(DM)<10−5.9 and c2vis,(DM)<10−5.7, with no detection of nondust properties for the DM.

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Notes : Acknowledgements. [...] The development of Planck was supported by: ...ASI