Dark energy and dark matter from an inhomogeneous dilaton

Abstract

A cosmological scenario is proposed where the dark matter (DM) and dark energy (DE) of the universe are two simultaneous manifestations of an inhomogenous dilaton. The equation of state of the field is scale-dependent and pressureless at galactic and larger scales and it has negative pressure as a DE at very large scales. The dilaton drives an inflationary phase followed by a kinetic energy-dominated one, as in the "quintessential inflation" model introduced by Peebles & Vilenkin, and soon after the end of inflation particle production seeds the first inhomogeneities that lead to galaxy formation. The dilaton is trapped near the minimum of the potential where it oscillates like a massive field, and the excess of kinetic energy is dissipated via the mechanism of "gravitational cooling" first introduced by Seidel & Suen. The inhomogeneities therefore behave like solitonic oscillations around the minimum of the potential, known as "oscillatons", that we propose account for most DM in galaxies. Those regions where the dilaton does not transform enough kinetic energy into reheating or carry an excess of it from regions that have cooled, evolve to the tail of the potential as DE, driving the acceleration of the universe.

9 pages, 8 figures, uses revtex, submitted PRD

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• A note on the relations between thermodynamics, energy definitions and Friedmann equations
• Reheating the Universe in Braneworld Cosmological Models with bulk-brane energy transfer
• A review on radiation of oscillons and oscillatons
• Exponential Potentials and Attractor Solution of Dilatonic Cosmology
• Dilaton Dark Energy Model in f(R), f(T) and Horava-Lifshitz Gravities
• Clustering GCG: a viable option for unified dark matter-dark energy?
• Higher Dimensional Cosmology with Some Dark Energy Models in Emergent, Logamediate and Intermediate Scenarios of the Universe