The radial BAO scale and Cosmic Shear, a new observable for Inhomogeneous Cosmologies

Abstract

As an alternative explanation of the dimming of distant supernovae it has recently been advocated that we live in a special place in the Universe near the centre of a large spherical void described by a Lemaitre-Tolman-Bondi (LTB) metric. In this scenario, the Universe is no longer homogeneous and isotropic, and the apparent late time acceleration is actually a consequence of spatial gradients. We propose in this paper a new observable, the normalized cosmic shear, written in terms of directly observable quantities, and calculable in arbitrary inhomogeneous cosmologies. This will allow future surveys to determine whether we live in a homogeneous universe or not. In this paper we also update our previous observational constraints from geometrical measures of the background cosmology. We include the Union Supernovae data set of 307 Type Ia supernovae, the CMB acoustic scale and the first measurement of the radial baryon acoustic oscillation scale. Even though the new data sets are significantly more constraining, LTB models -- albeit with slightly larger voids -- are still in excellent agreement with observations, at chi^2/d.o.f. = 307.7/(310-4)=1.005. Together with the paper we also publish the updated easyLTB code used for calculating the models and for comparing them to the observations.

18 pages, 8 figures, the code can be downloaded at http://www.phys.au.dk/~haugboel/software.shtml

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Cited by in corpus (17)

• Testing the Void against Cosmological data: fitting CMB, BAO, SN and H0
• Precision cosmology defeats void models for acceleration
• A new perspective on Dark Energy modeling via Genetic Algorithms
• The Cosmic Microwave Background in an Inhomogeneous Universe - why void models of dark energy are only weakly constrained by the CMB
• Redshift Drift in LTB Void Universes
• Observational constraints on the LLTB model
• The Copernican principle in light of the latest cosmological data
• Euclid: Forecast constraints on consistency tests of the $\Lambda$CDM model
• Galaxy correlations and the BAO in a void universe: structure formation as a test of the Copernican Principle
• Spatial and temporal tuning in void models for acceleration
• The phase space analysis of modified gravity (MOG)
• Reconstruction of the null-test for the matter density perturbations
• Halo abundances and shear in void models
• DESIgning concordant distances in the age of precision cosmology: the impact of density fluctuations
• Evolution of linear perturbations in Lemaître-Tolman-Bondi void models
• Comparison of two approximation schemes for solving perturbations in a LTB cosmological model
• Forecast constraints on null tests of the $\Lambda$CDM model with SPHEREx