The radial BAO scale and cosmic shear, a new observable for inhomogeneous cosmologies

Journal Article · Tue Sep 01 04:00:00 EDT 2009 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2009/09/028· OSTI ID:22273040

García-Bellido, Juan ^[1]; Haugbølle, Troels ^[2]

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1. Instituto de Física Teórica UAM-CSIC, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain)
2. Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark)

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 Lemaître-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 agreement with observations, at χ{sup 2}/d.o.f. = 309.1/(310−4) = 1.01. Together with the paper we also publish the updated easyLTB code used for calculating the models and for comparing them to the observations.

• OSTI ID: 22273040
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 09 Vol. 2009; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCELERATION
ASTROPHYSICS
BARYONS
COMPARATIVE EVALUATIONS
COSMOLOGY
LIMITING VALUES
METRICS
OSCILLATIONS
PUBLIC OPINION
SHEAR
SPHERICAL CONFIGURATION
SUPERNOVAE
UNIVERSE