Dynamical spatial curvature as a fit to Type Ia supernovae

Abstract

Few statements in cosmology can be made without assuming a cosmological model within which to interpret data. Statements about cosmic acceleration are no exception to this rule, and the inferred positive volume acceleration of our Universe often quoted in the literature is valid in the context of the standard Friedmann-Lemaître-Robertson-Walker (FLRW) class of space-times.Using the Joint Light-curve Analysis (JLA) catalogue of type Ia supernovae (SNIa), we examine the fit of a class of exact scaling solutions with dynamical spatial curvature formulated in the framework of a scalar averaging scheme for relativistic inhomogeneous space-times. In these models, global volume acceleration may emerge as a result of the non-local variance between expansion rates of clusters and voids, the latter gaining volume dominance in the late-epoch Universe.We find best-fit parameters for a scaling model of backreaction that are reasonably consistent with previously found constraints from SNIa, CMB, and baryon acoustic oscillations data. The quality of fit of the scaling solutions is indistinguishable from that of the ΛCDM model and the timescape cosmology from an Akaike Information Criterion (AIC) perspective. This indicates that a broad class of models can account for the z 1 expansion history.

Construction of the cosmological model with periodically distributed inhomogeneities with growing amplitude

“…There are also works which do not confirm the irrelevance of inhomogeneities despite similar methods and techniques used in studies [37][38][39]. Moreover, it is argued that the phenomena of virialization of clusters and volume dominance of voids significantly affect the Hubble diagram and may even explain dark energy [40][41][42][43][44].…”

Theoretical cosmology

“…Observationally, and based on the 2-point correlation function, the smallest scale at which any measure of statistical homogeneity can emerge by the current epoch is in the range 70-120 h −1 M pc. Indeed, if all N-point correlations of the galaxy distribution are considered, then the homogeneity scale can only be reached, if at all, on scales above 700 h −1 M pc [116] (also see [229]).…”

“…It should be emphasised that the fact that structure formation implies that the present-day Universe (is volume-dominated by voids and) is characterized by on average negative curvature is a subtle issue that follows from the result that intrinsic curvature does not obey a conservation law [118,229]. Indeed, it dispels the naive expectation that on large scales the distribution of positive spatial curvature for high-density regions and negative spatial curvature for the voids, averages out to the almost or exactly zero spatial curvature assumed.…”

Gauss-Bonnet-Chern approach to the averaged Universe

“…references in the introduction, or to model curvature evolution to explain observational data without dark energy, e.g. [48], or in perturbation theories. Indeed, a closure by the global stationarity assumption äΣ = 0, yields solutions of the form (51) for N = 3 [28].…”