Correspondence between kinematical backreaction and scalar field cosmologies - the `morphon field'

Abstract

Spatially averaged inhomogeneous cosmologies in classical general relativity can be written in the form of effective Friedmann equations with sources that include backreaction terms. In this paper we propose to describe these backreaction terms with the help of a homogeneous scalar field evolving in a potential; we call it the `morphon field'. This new field links classical inhomogeneous cosmologies to scalar field cosmologies, allowing to reinterpret, e.g., quintessence scenarios by routing the physical origin of the scalar field source to inhomogeneities in the Universe. We investigate a one-parameter family of scaling solutions to the backreaction problem. Subcases of these solutions (all without an assumed cosmological constant) include scale-dependent models with Friedmannian kinematics that can mimic the presence of a cosmological constant or a time-dependent cosmological term. We explicitly reconstruct the scalar field potential for the scaling solutions, and discuss those cases that provide a solution to the Dark Energy and coincidence problems. In this approach, Dark Energy emerges from morphon fields, a mechanism that can be understood through the proposed correspondence: the averaged cosmology is characterized by a weak decay (quintessence) or growth (phantom quintessence) of kinematical fluctuations, fed by `curvature energy' that is stored in the averaged 3-Ricci curvature. We find that the late-time trajectories of those models approach attractors that lie in the future of a state that is predicted by observational constraints.

36 pages and 6 Figures, matches published version in Class.Quant.Grav

References in corpus (10)

• The universe seen at different scales
• Challenges for scaling cosmologies
• Constraints on backreaction in dust universes
• Adhesive Gravitational Clustering
• Information Entropy in Cosmology
• Dark Energy: Recent Developments
• A cosmic equation of state for the inhomogeneous Universe: can a global far-from-equilibrium state explain Dark Energy?
• Geometrical Constraints on Dark Energy
• A rule of thumb for cosmological backreaction
• Scaling solutions and geodesics in moduli space

Cited by in corpus (23)

• Cosmic clocks, cosmic variance and cosmic averages
• On causality and superluminal behavior in classical field theories. Applications to k-essence theories and MOND-like theories of gravity
• Light-cone averages in a swiss-cheese universe
• Scale dependence of cosmological backreaction
• The Possibility of Cosmic Acceleration via Spatial Averaging in Lemaitre-Tolman-Bondi Models
• Evaluating backreaction with the peak model of structure formation
• On the curvature of the present-day Universe
• The influence of structure formation on the cosmic expansion
• Cosmological equivalence principle and the weak-field limit
• Cosmological Backreaction from Perturbations
• The Spatial Averaging Limit of Covariant Macroscopic Gravity - Scalar Corrections to the Cosmological Equations
• Apparent and average acceleration of the Universe
• Toward a Unified Description of Dark Energy and Dark Matter from the Abnormally Weighting Energy Hypothesis
• Explicit Cosmological Coarse Graining via Spatial Averaging
• Position and frequency shifts induced by massive modes of the gravitational wave background in alternative gravity
• Averaging Robertson-Walker Cosmologies
• Backreaction of Cosmological Perturbations in Covariant Macroscopic Gravity
• Is dark energy an effect of averaging?
• Volume averaging in the quasispherical Szekeres model
• Scaling cosmologies, geodesic motion and pseudo-susy
• Scaling Cosmologies of N=8 Gauged Supergravity
• Averaging anisotropic cosmologies
• Averaging inhomogeneities in scalar-tensor cosmology