Coupled and Extended Quintessence: theoretical differences and structure formation

Abstract

The case of a coupling between dark energy and matter (Coupled Quintessence) or gravity (Extended Quintessence) has recently attracted a deep interest and has been widely investigated both in the Einstein and in the Jordan frames (EF, JF), within scalar tensor theories. Focusing on the simplest models proposed so far, in this paper we study the relation existing between the two scenarios, isolating the Weyl scaling which allows to express them in the EF and JF. Moreover, we perform a comparative study of the behavior of linear perturbations in both scenarios, which turn out to behave in a markedly different way. In particular, while the clustering is enhanced in the considered CQ models with respect to the corresponding Quintessence ones where the coupling is absent and to the ordinary cosmologies with a Cosmological Constant and Cold Dark Matter (LCDM), structures in EQ models may grow slower. This is likely to have direct consequences on the inner properties of non-linear structures, like cluster concentration, as well as on the weak lensing shear on large scales. Finally, we specialize our study for interfacing linear dynamics and N-body simulations in these cosmologies, giving a recipe for the corrections to be included in N-body codes in order to take into account the modifications to the expansion rate, growth of structures, and strength of gravity.

19 pages, 4 figures. References added, minor changes, published in PRD

References in corpus (12)

• Dynamics of dark energy with a coupling to dark matter
• Consequences of dark matter-dark energy interaction on cosmological parameters derived from SNIa data
• de Sitter space and the equivalence between f(R) and scalar-tensor gravity
• Growing Matter
• Signature of the interaction between dark energy and dark matter in galaxy clusters
• Growing neutrinos and cosmological selection
• Adiabatic instability in coupled dark energy-dark matter models
• Neutrino Dark Energy -- Revisiting the Stability Issue
• Neutrino clustering in growing neutrino quintessence
• New interactions in the dark sector mediated by dark energy
• The Integrated Sachs-Wolfe Effect in Interacting Dark Energy Models
• Dark Matter & Dark Energy from a single scalar field: CMB spectrum and matter transfer function

Cited by in corpus (5)

• Interacting models may be key to solve the cosmic coincidence problem
• The Growth of Structure in Interacting Dark Energy Models
• Do WMAP data favor neutrino mass and a coupling between Cold Dark Matter and Dark Energy?
• Late universe dynamics with scale-independent linear couplings in the dark sector
• Growing neutrino cosmology