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The MESS of the CMB. (English) Zbl 1484.83135

Summary: We analyze cosmic microwave background (CMB) data taking into account the effects of a momentum dependent effective sound speed (MESS). This approach allows to study the effects of primordial entropy perturbations in a model independent way, and its implementation requires a minimal modification of existing CMB fitting numerical codes developed for single scalar field models.
We adopt a phenomenological approach, and study the effects of a local variation of the MESS around the scale where other analysis have shown some deviation from an approximately scale invariant curvature perturbation spectrum. We obtain a substantial improvement of the fit with respect to a model without MESS, showing that primordial entropy perturbations can be an explanation of these deviations.

MSC:

83F05 Relativistic cosmology
35B20 Perturbations in context of PDEs
83E05 Geometrodynamics and the holographic principle
83C55 Macroscopic interaction of the gravitational field with matter (hydrodynamics, etc.)
76Q05 Hydro- and aero-acoustics
53C21 Methods of global Riemannian geometry, including PDE methods; curvature restrictions
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