Cosmological backreaction within the Szekeres model and emergence of spatial curvature

Abstract

This paper discusses the phenomenon of backreaction within the Szekeres model. Cosmological backreaction describes how the mean global evolution of the Universe deviates from the Friedmannian evolution. The analysis is based on models of a single cosmological environment and the global ensemble of the Szekeres models (of the Swiss-Cheese-type and Styrofoam-type). The obtained results show that non-linear growth of cosmic structures is associated with the growth of the spatial curvature ${\Omega }_{\mathcal{R}}$ (in the FLRW limit ${\Omega }_{\mathcal{R}}\to {\Omega }_k$). If averaged over global scales the result depends on the assumed global model of the Universe. Within the Swiss-Cheese model, which does have a fixed background, the volume average follows the evolution of the background, and the global spatial curvature averages out to zero (the background model is the $\Lambda$CDM model, which is spatially flat). In the Styrofoam-type model, which does not have a fixed background, the mean evolution deviates from the spatially flat $\Lambda$CDM model, and the mean spatial curvature evolves to from ${\Omega }_{\mathcal{R}}=0$ at the CMB to ${\Omega }_{\mathcal{R}}\sim 0.1$ at $z=0$. If the Styrofoam-type model correctly captures evolutionary features of the real Universe then one should expect that in our Universe, the spatial curvature should build up (local growth of cosmic structures) and its mean global average should deviate from zero (backreaction). As a result, this paper predicts that the low-redshift Universe should not be spatially flat (i.e. ${\Omega }_k\ne 0$, even if in the early Universe ${\Omega }_k=0$) and therefore when analysing low-$z$ cosmological data one should keep ${\Omega }_k$ as a free parameter and independent from the CMB constraints.

23 pages, 7 figures; v3 - matches published version

References in corpus (20)

• Relativistic cosmology and large-scale structure
• Cosmic clocks, cosmic variance and cosmic averages
• The universe seen at different scales
• Accelerated expansion from structure formation
• A new framework for analyzing the effects of small scale inhomogeneities in cosmology
• How well is our universe described by an FLRW model?
• What is dust? - Physical foundations of the averaging problem in cosmology
• Correspondence between kinematical backreaction and scalar field cosmologies - the `morphon field'
• Multiscale cosmology and structure-emerging Dark Energy: A plausibility analysis
• Evaluating backreaction with the peak model of structure formation
• Inhomogeneous Cosmology with Numerical Relativity
• N-body methods for relativistic cosmology
• Concordance cosmology without dark energy
• Dynamics of astrophysical objects against the cosmological background
• The tangential velocity excess of the Milky Way satellites
• Hubble flows and gravitational potentials in observable Universe
• Inhomogeneous cosmology and backreaction: Current status and future prospects
• On Backreaction in Newtonian cosmology
• Discrete Newtonian Cosmology: Perturbations
• The background Friedmannian Hubble constant in relativistic inhomogeneous cosmology and the age of the Universe

Cited by in corpus (16)

• Inflation after Planck: Judgment Day
• On average properties of inhomogeneous fluids in general relativity III: general fluid cosmologies
• Relativistic numerical cosmology with Silent Universes
• On Backreaction in Newtonian cosmology
• An effective description of Laniakea: impact on cosmology and the local determination of the Hubble constant
• Towards statistically homogeneous and isotropic perfect fluid universes with cosmic backreaction
• Cosmological backreaction and its dependence on spacetime foliation
• Numerical solutions to Einstein's equations in a shearing-dust Universe: a code comparison
• Replacing dark energy by silent virialisation
• A novel approach to cosmological non-linearities as an effective fluid
• Emergence of spatial curvature
• Black hole formation from the gravitational collapse of a non-spherical network of structures
• Does spatial flatness forbid the turnaround epoch of collapsing structures?
• Multiple-Scales Approach to The Averaging Problem in Cosmology
• Rotation, Embedding and Topology for the Szekeres Geometry
• Does relativistic cosmology software handle emergent volume evolution?