Expansion and Growth of Structure Observables in a Macroscopic Gravity Averaged Universe

Abstract

We investigate the effect of averaging inhomogeneities on expansion and large-scale structure growth observables using the exact and covariant framework of Macroscopic Gravity (MG). It is well-known that applying the Einstein's equations and spatial averaging do not commute and lead to the averaging problem. For the MG formalism applied to the Friedmann-Lemaitre-Robertson-Walker (FLRW) metric, this gives an extra dynamical term encapsulated as an averaging density parameter denoted ${\Omega }_A$. An exact isotropic cosmological solution of MG for the flat FLRW metric is already known in the literature, we derive here an anisotropic exact solution. Using the isotropic solution, we compare the expansion history to current data of distances to supernovae, Baryon Acoustic Oscillations, CMB last scattering surface, and Hubble constant measurements, and find $-0.05\le {\Omega }_A\le 0.07$ (at the 95% CL). For the flat metric case this reduces to $-0.03\le {\Omega }_A\le 0.05$. We also find that the inclusion of this term in the fits can shift the values of the usual cosmological parameters by a few to several percents. Next, we derive an equation for the growth rate of large scale structure in MG that includes a term due to the averaging and compare it to that of the LCDM concordance model. We find that an ${\Omega }_A$ of an amplitude range within the bounds above leads to a relative deviation of the growth from that of the LCDM of up to 2-4% at late times. Thus, the shift in the growth could be of comparable amplitude to that caused by similar changes in cosmological parameters like the dark energy density parameter or its equation of state. The effect could also be comparable in amplitude to some systematic effects considered for future surveys. This indicates that the averaging term and its possible effect need to be tightly constrained in future precision cosmological studies. (Abridged)

arXiv comment18 pages, 3 figures, to appear in Phys.Rev.D

References in corpus (93)

• Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results
• Detection of the Baryon Acoustic Peak in the Large-Scale Correlation Function of SDSS Luminous Red Galaxies
• Cosmological parameters from CMB and other data: a Monte-Carlo approach
• The 2dF Galaxy Redshift Survey: Spectra and redshifts
• The Hubble Space Telescope Cluster Supernova Survey: V. Improving the Dark Energy Constraints Above z>1 and Building an Early-Type-Hosted Supernova Sample
• Cosmological Constraints from the SDSS Luminous Red Galaxies
• The WiggleZ Dark Energy Survey: mapping the distance-redshift relation with baryon acoustic oscillations
• Small Scale Cosmological Perturbations: An Analytic Approach
• A Redetermination of the Hubble Constant with the Hubble Space Telescope from a Differential Distance Ladder
• Cosmic Growth History and Expansion History
• First-year Sloan Digital Sky Survey-II (SDSS-II) Supernova Results: Hubble Diagram and Cosmological Parameters
• A test of the nature of cosmic acceleration using galaxy redshift distortions
• Cosmological Non-Linearities as an Effective Fluid
• On average properties of inhomogeneous fluids in general relativity I: dust cosmologies
• The WiggleZ Dark Energy Survey: the growth rate of cosmic structure since redshift z=0.9
• The Linear Theory Power Spectrum from the Lyman-alpha Forest in the Sloan Digital Sky Survey
• The Energy-Momentum Tensor for Cosmological Perturbations
• Inferring the dark matter power spectrum from the Lyman-alpha forest in high-resolution QSO absorption spectra
• On average properties of inhomogeneous fluids in general relativity II: perfect fluid cosmologies
• On cosmic acceleration without dark energy
• The 2dF-SDSS LRG and QSO Survey: QSO clustering and the L-z degeneracy
• Cosmic clocks, cosmic variance and cosmic averages
• The 2dF-SDSS LRG and QSO Survey: The LRG 2-Point Correlation Function and Redshift-Space Distortions
• Can the Acceleration of Our Universe Be Explained by the Effects of Inhomogeneities?
• Cosmological and astrophysical parameters from the SDSS flux power spectrum and hydrodynamical simulations of the Lyman-alpha forest
• The effect of inhomogeneous expansion on the supernova observations
• A new framework for analyzing the effects of small scale inhomogeneities in cosmology
• On the growth of linear perturbations
• Light-cone averaging in cosmology: formalism and applications
• Cosmological Solutions in Macroscopic Gravity
• (Mis-)Interpreting supernovae observations in a lumpy universe
• Testing backreaction effects with observations
• Cosmological parameters are dressed
• Can superhorizon cosmological perturbations explain the acceleration of the universe?
• Light-cone averages in a swiss-cheese universe
• Light propagation in statistically homogeneous and isotropic universes with general matter content
• Scale dependence of cosmological backreaction
• Multiscale cosmology and structure-emerging Dark Energy: A plausibility analysis
• The growth of matter perturbations in some scalar-tensor DE models
• Evaluating backreaction with the peak model of structure formation
• Observed galaxy number counts on the lightcone up to second order: I. Main result
• Average expansion rate and light propagation in a cosmological Tardis spacetime
• Can superhorizon perturbations drive the acceleration of the Universe?
• Falsifying Paradigms for Cosmic Acceleration
• Can Structure Formation Influence the Cosmological Evolution?
• A Renormalization Group Approach to Relativistic Cosmology
• Do Large-Scale Inhomogeneities Explain Away Dark Energy?
• Is backreaction really small within concordance cosmology?
• Spatially averaged cosmology in an arbitrary coordinate system
• Cosmological Backreaction from Perturbations
• Evolution of cosmic structures in different environments in the quasispherical Szekeres model
• Age of the Universe: Influence of the Inhomogeneities on the global Expansion-Factor
• The Spatial Averaging Limit of Covariant Macroscopic Gravity - Scalar Corrections to the Cosmological Equations
• Growth factor parametrization in curved space
• Cosmic spherical void via coarse-graining and averaging non-spherical structures
• Averaging in Cosmology
• Averaging in Spherically Symmetric Cosmology
• Back-reaction and effective acceleration in generic LTB dust models
• Contiguous redshift parameterizations of the growth index
• Space-time Averages in Macroscopic Gravity and Volume-preserving Coordinates
• Constraints on growth index parameters from current and future observations
• Local and non-local measures of acceleration in cosmology
• Cosmic Inhomogeneities and the Average Cosmological Dynamics
• Exact Evolution of Discrete Relativistic Cosmological Models
• Effects of Inhomogeneities on Cosmic Expansion
• Light propagation and the average expansion rate in near-FRW universes
• Averaging Spherically Symmetric Spacetimes in General Relativity
• Backreaction of Cosmological Perturbations in Covariant Macroscopic Gravity
• Covariant coarse-graining of inhomogeneous dust flow in General Relativity
• A Complete Cosmological Solution to the Averaged Einstein Field Equations as found in Macroscopic Gravity
• Large-scale growth evolution in the Szekeres inhomogeneous cosmological models with comparison to growth data
• The Hubble rate in averaged cosmology
• Averaging geometrical objects on a differentiable manifold
• Light Propagation in Inhomogeneous Universes II. Cosmological Parameter Survey
• Observational Constraints on the Averaged Universe
• Violation of the FRW consistency condition as a signature of backreaction
• Non-linear relativistic contributions to the cosmological weak-lensing convergence
• Apparent Acceleration through Large-scale Inhomogeneities --Post-Friedmannian Effects of Inhomogeneities on the Luminosity Distance--
• Averaging in cosmological models using scalars
• Exploiting scale dependence in cosmological averaging
• Spherically Symmetric Solutions in Macroscopic Gravity
• The Gravitational Polarization in General Relativity: Solution to Szekeres' Model of Quadrupole Polarization
• Light propagation in the averaged universe
• General K=-1 Friedman-Lemaître models and the averaging problem in cosmology
• Back Reaction from Walls
• Backreaction: Gauge and Frame Dependences
• Effects of anisotropy on gravitational infall in galaxy clusters using an exact general relativistic model
• On the physical effects of consistent cosmological averaging
• A Phantom does not Result from a Backreaction
• Criticality and Averaging in Cosmology
• Observational Cosmology in Macroscopic Gravity
• Evolution of the discrepancy between a universe and its model

Cited by in corpus (5)

• Testing General Relativity in Cosmology
• Averaged universe confronted with cosmological observations: A fully covariant approach
• On the Effects of Non-metricity in an Averaged Universe
• An Almost-FLRW Universe as the Averaged Geometry in Macroscopic Gravity
• Spherical and Plane Symmetric Solutions in Macroscopic Gravity