paper

Constraining dark matter properties with Cosmic Microwave Background observations

arXiv:1601.05097 · doi:10.3847/0004-637X/830/2/155

Abstract

We examine how the properties of dark matter, parameterised by an equation of state parameter and two perturbative Generalised Dark Matter (GDM) parameters (the sound speed) and (the viscosity), are constrained by existing cosmological data, particularly the Planck 2015 data release. We find that the GDM parameters are consistent with zero, and are strongly constrained, showing no evidence for extending the dark matter model beyond the Cold Dark Matter (CDM) paradigm. The dark matter equation of state is constrained to be within at the confidence level, which is several times stronger than constraints found previously using WMAP data. The parameters and are constrained to be less than and respectively at the confidence level. The inclusion of the GDM parameters does significantly affect the error bars on several CDM parameters, notably the dimensionless dark matter density and the derived parameters and . This can be partially alleviated with the inclusion of data constraining the expansion history of the universe.

12 pages, 10 figures, 2 tables, updated to match the version published in ApJ

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