Cosmic Acceleration from Causal Backreaction in a Smoothly Inhomogeneous Universe

Abstract

A phenomenological formalism is presented in which the apparent acceleration of the universe is generated by large-scale structure formation, thus eliminating the coincidence and magnitude fine-tuning problems of the Cosmological Constant in the Concordance Model, as well as potential instability issues with dynamical Dark Energy. The observed acceleration results from the combined effect of innumerable local perturbations, due to individually virialized systems, overlapping together in a smoothly-inhomogeneous adjustment of the FRW metric, in a process governed by the causal flow of inhomogeneity information outward from each clumped system. We discuss several arguments from the literature claiming to place sharp limits upon the strength of backreaction-related effects, and show why such arguments are not applicable in a physically realistic cosmological analysis. A selection of simply-parameterized models are presented, including several which are capable of fitting the luminosity distance data from Type Ia supernovae essentially as well as the best-fit flat $\Lambda$CDM model, without resort to Dark Energy, any modification to gravity, or a local void. Simultaneously, these models can reproduce measured cosmological parameters such as the age of the universe, the matter density required for spatial flatness, the present-day deceleration parameter, and the angular scale of the Cosmic Microwave Background to within a reasonable proximity of their Concordance values. We conclude by considering potential observational signatures for distinguishing this cosmological formalism from $\Lambda$CDM or Dark Energy, as well as the possible long-term fate of such a universe with ever-spreading spheres of influence for its increasingly superposed perturbations.

103 pages, 6 figures, 1 table. v2 & v3: citation updates, with some discussion and references added. An early exposition of this research, with preliminary results, was presented as a poster at the 23rd Texas Symposium on Relativistic Astrophysics, Melbourne, Australia (December 2006)

References in corpus (36)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• New Hubble Space Telescope Discoveries of Type Ia Supernovae at z > 1: Narrowing Constraints on the Early Behavior of Dark Energy
• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Data Processing, Sky Maps, and Basic Results
• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Likelihoods and Parameters from the WMAP data
• Improved Cosmological Constraints from New, Old and Combined Supernova Datasets
• A 3% Solution: Determination of the Hubble Constant with the Hubble Space Telescope and Wide Field Camera 3
• Spectra and Light Curves of Six Type Ia Supernovae at 0.511 < z < 1.12 and the Union2 Compilation
• Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Temperature Analysis
• Improved Dark Energy Constraints from ~100 New CfA Supernova Type Ia Light Curves
• CfA3: 185 Type Ia Supernova Light Curves from the CfA
• The Observed properties of Dark Matter on small spatial scales
• Correlation of CMB with large-scale structure: I. ISW Tomography and Cosmological Implications
• COSMOS: 3D weak lensing and the growth of structure
• The non-Gaussian Cold Spot in the 3-year WMAP data
• On cosmological observables in a swiss-cheese universe
• McVittie's Legacy: Black Holes in an Expanding Universe
• Living in a Void: Testing the Copernican Principle with Distant Supernovae
• Cosmographic Hubble fits to the supernova data
• The Collision Between The Milky Way And Andromeda
• Neutrino Dark Energy -- Revisiting the Stability Issue
• Anisotropy in the Hubble constant as observed in the HST Extragalactic Distance Scale Key Project results
• Voids of dark energy
• Description of our cosmological spacetime as a perturbed conformal Newtonian metric and implications for the backreaction proposal for the accelerating universe
• Accelerated expansion without dark energy
• Gravitational Backreaction of Matter Inhomogeneities
• Light propagation and the average expansion rate in near-FRW universes
• Primordial inflation explains why the universe is accelerating today
• Toward a No-Go Theorem for an Accelerating Universe through a Nonlinear Backreaction
• The Great Attractor and the Shapley Concentration
• The Cosmological Parameters 2014
• Spherical collapse with dark energy
• Perturbations to the Cosmological Expansion in a Grainy Universe
• Optimal covariant fitting to a Robertson-Walker metric and smallness of backreaction
• Beta, Local SNIa data and the Great Attractor
• On the Accelerated Expansion of the Universe

Cited by in corpus (3)

• Testing Lambda and the Limits of Cosmography with the Union2.1 Supernova Compilation
• Taylor expansion of luminosity distance in Szekeres cosmological models: Effects of local structures evolution on cosmographic parameters
• Cosmic Acceleration and a New Concordance from Causal Backreaction