Inhomogeneity implies accelerated expansion

  title={Inhomogeneity implies accelerated expansion},
  author={Harald Skarke},
  journal={Physical Review D},
  • H. Skarke
  • Published 3 October 2013
  • Physics
  • Physical Review D
The Einstein equations for an inhomogeneous irrotational dust universe are analyzed. A set of mild assumptions, all of which are shared by the standard Friedmann-Lemaitre-Robertson-Walker\char21{}type scenarios, results in a model that depends only on the distribution of scalar spatial curvature. If the shape of this distribution is made to fit the structure of the present Universe, with most of the matter in galaxy clusters and very little in the voids that will eventually dominate the volume… 

Evolution of an inhomogeneous universe

A refined version of a recently introduced method for analysing the dynamics of an inhomogeneous irrotational dust universe is presented. A fully non-perturbative numerical computation of the time

Cosmic acceleration as an optical illusion

We consider light propagation in an inhomogeneous irrotational dust universe with vanishing cosmological constant, with initial conditions as in standard linear perturbation theory. A

Light propagation in the averaged universe

Cosmic structures determine how light propagates through the Universe and consequently must be taken into account in the interpretation of observations. In the standard cosmological model at the

Future evolution in a backreaction model and the analogous scalar field cosmology

We investigate the future evolution of the universe using the Buchert framework for averaged backreaction in the context of a two-domain partition of the universe. We show that this approach allows

Cosmic bulk viscosity through backreaction

We consider an effective viscous pressure as the result of a backreaction of inhomogeneities within Buchert’s formalism. The use of an effective metric with a time-dependent curvature radius allows

Light in the inhomogeneous Universe: studies on light propagation in the averaged space-time

In standard cosmology a background geometry is used to interpret observations of the large scale structure of the Universe. The background means a homogeneous, isotropic and flat Friedmann-Lemaitre

Constraining cosmic curvature by using age of galaxies and gravitational lenses

We use two model-independent methods to constrain the curvature of the universe. In the first method, we study the evolution of the curvature parameter (Ωk0) with redshift by using the observations

On the covariance of scalar averaging and backreaction in relativistic inhomogeneous cosmology

We introduce a generalization of the 4-dimensional averaging window function of Gasperini et al (2010 J. Cosmol. Astropart. Phys. JCAP02(2010)009) that may prove useful for a number of applications.

Measurement of marked correlation functions in SDSS-III Baryon Oscillation Spectroscopic Survey using LOWZ galaxies in Data Release 12

Marked correlation functions, which are sensitive to the clustering of galaxies in different environments, have been proposed as constraints on modified gravity models. We present measurements of the



On Average Properties of Inhomogeneous Fluids in General Relativity: Dust Cosmologies

For general relativistic spacetimes filled with irrotational ‘dust’ a generalized form of Friedmann's equations for an ‘effective’ expansion factor aD of inhomogeneous cosmologies is derived.

Accelerated expansion from structure formation

We discuss the physics of backreaction-driven accelerated expansion. Using the exact equations for the behaviour of averages in dust universes, we explain how large-scale smoothness does not imply

On cosmic acceleration without dark energy

We elaborate on the proposal that the observed acceleration of the Universe is the result of the backreaction of cosmological perturbations, rather than the effect of a negative-pressure dark-energy

Onset of cosmological backreaction

Cosmological backreaction has been suggested as an explanation of dark energy and is heavily disputed since. We combine cosmological perturbation theory with Buchert's nonperturbative framework,

Comment about quasi-isotropic solution of Einstein equations near the cosmological singularity

For the case of arbitrary hydrodynamical matter, we generalize the quasi-isotropic solution of Einstein equations near the cosmological singularity, found by Lifshitz and Khalatnikov in 1960 for the

Does the growth of structure affect our dynamical models of the Universe? The averaging, backreaction, and fitting problems in cosmology

Structure occurs over a vast range of scales in the Universe. Our large-scale cosmological models are coarse-grained representations of what exists, which have much less structure than there really

Dark Energy from structure: a status report

The effective evolution of an inhomogeneous universe model in any theory of gravitation may be described in terms of spatially averaged variables. In Einstein’s theory, restricting attention to

The Cosmic Baryon Budget

We present an estimate of the global budget of baryons in all states, with conservative estimates of the uncertainties, based on all relevant information we have been able to marshal. Most of the

Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant

We present spectral and photometric observations of 10 Type Ia supernovae (SNe Ia) in the redshift range 0.16 ≤ z ≤ 0.62. The luminosity distances of these objects are determined by methods that