Backreaction as an alternative to dark energy and modified gravity

Abstract

The predictions of homogeneous and isotropic cosmological models with ordinary matter and gravity are off by a factor of two in the late universe. One possible explanation is the known breakdown of homogeneity and isotropy due to the formation of non-linear structures. We review how inhomogeneities affect the average expansion rate and can lead to acceleration, and consider a semi-realistic model where the observed timescale of ten billion years emerges from structure formation. We also discuss the relation between the average expansion rate and observed quantities.

22 pages, 4 figures. Contribution to the proceedings of the "Beyond the Concordance Model" workshop held at The Stellenbosch Institute for Advanced Study, 23.-27. August 2010

References in corpus (15)

• The Hubble Constant: A Summary of the HST Program for the Luminosity Calibration of Type Ia Supernovae by Means of Cepheids
• Relativistic cosmology and large-scale structure
• A general test of the Copernican Principle
• The universe seen at different scales
• Vector field models of modified gravity and the dark sector
• Constraints on backreaction in dust universes
• Can inhomogeneties accelerate the cosmic volume expansion?
• First Cosmological Constraints on Dark Energy from the Radial Baryon Acoustic Scale
• Applicability of the linearly perturbed FRW metric and Newtonian cosmology
• The expansion field: The value of H_0
• Accelerated expansion without dark energy
• Have Baryonic Acoustic Oscillations in the galaxy distribution really been measured?
• Alternatives to dark matter: Modified gravity as an alternative to dark matter
• Backreaction of linear perturbations and dark energy
• Breaking of self-averaging properties and selection effects in the Luminous Red Galaxies sample

Cited by in corpus (7)

• Average expansion rate and light propagation in a cosmological Tardis spacetime
• Light propagation and the average expansion rate in near-FRW universes
• Quantum Corrections to the Gravitational Backreaction
• Stephani Cosmology: Entropically Viable But Observationally Challenged
• Backreaction and the Covariant Formalism of General Relativity
• Cosmic Acceleration and a New Concordance from Causal Backreaction
• Acceleration from a clustering environment