Large scale structure from viscous dark matter
Cosmological perturbations of sufficiently long wavelength admit a fluid dynamic description. We consider modes with wavevectors below a scale k m for which the dynamics is only mildly non-linear. The leading effect of modes above that scale can be accounted for by effective non-equilibrium viscosit...
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| Main Authors: | , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
30 November 2015
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| In: |
Journal of cosmology and astroparticle physics
Year: 2015, Issue: 11, Pages: 1-30 |
| ISSN: | 1475-7516 |
| DOI: | 10.1088/1475-7516/2015/11/049 |
| Online Access: | Verlag, Volltext: http://dx.doi.org/10.1088/1475-7516/2015/11/049 Verlag, Volltext: http://stacks.iop.org/1475-7516/2015/i=11/a=049 
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| Author Notes: | Diego Blas, Stefan Floerchinger, Mathias Garny, Nikolaos Tetradis and Urs Achim Wiedemann |
| Summary: | Cosmological perturbations of sufficiently long wavelength admit a fluid dynamic description. We consider modes with wavevectors below a scale k m for which the dynamics is only mildly non-linear. The leading effect of modes above that scale can be accounted for by effective non-equilibrium viscosity and pressure terms. For mildly non-linear scales, these mainly arise from momentum transport within the ideal and cold but inhomogeneous fluid, while momentum transport due to more microscopic degrees of freedom is suppressed. As a consequence, concrete expressions with no free parameters, except the matching scale k m , can be derived from matching evolution equations to standard cosmological perturbation theory. Two-loop calculations of the matter power spectrum in the viscous theory lead to excellent agreement with N -body simulations up to scales k=0.2 h /Mpc. The convergence properties in the ultraviolet are better than for standard perturbation theory and the results are robust with respect to variations of the matching scale. |
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| Item Description: | Gesehen am 24.11.2017 |
| Physical Description: | Online Resource |
| ISSN: | 1475-7516 |
| DOI: | 10.1088/1475-7516/2015/11/049 |