Non-minimally coupled dark matter: effective pressure and structure formation

Abstract

We propose a phenomenological model in which a non-minimal coupling between gravity and dark matter is present in order to address some of the apparent small scales issues of \lcdm model. When described in a frame in which gravity dynamics is given by the standard Einstein-Hilbert action, the non-minimal coupling translates into an effective pressure for the dark matter component. We consider some phenomenological examples and describe both background and linear perturbations. We show that the presence of an effective pressure may lead these scenarios to differ from \lcdm at the scales where the non-minimal coupling (and therefore the pressure) is active. In particular two effects are present: a pressure term for the dark matter component that is able to reduce the growth of structures at galactic scales, possibly reconciling simulations and observations; an effective interaction term between dark matter and baryons that could explain observed correlations between the two components of the cosmic fluid within Tully-Fisher analysis.

18 pages, 6 figures, references added. Published in JCAP

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Cited by in corpus (7)

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• Soundness of Dark Energy properties
• Disformal transformation of cosmological perturbations
• Testing Dark Matter Clustering with Redshift Space Distortions
• Self-gravitating Equilibria of Non-minimally Coupled Dark Matter Halos
• Empirical Evidence of Non-Minimally Coupled Dark Matter in the Dynamics of Local Spiral Galaxies?
• Potential-driven Inflation with Disformal Coupling to Gravity