LTB universes as alternatives to dark energy: does positive averaged acceleration imply positive cosmic acceleration?

Abstract

We show that positive averaged acceleration obtained in LTB models through spatial averaging can require integration over a region beyond the event horizon of the central observer. We provide an example of a LTB model with positive averaged acceleration in which the luminosity distance does not contain information about the entire spatially averaged region, making the averaged acceleration unobservable. Since the cosmic acceleration is obtained from fitting the observed luminosity distance to a FRW model we conclude that in general a positive averaged acceleration in LTB models does not imply a positive FRW cosmic acceleration.

10 pages, 5 figures, Added some notation clarifications and references, Accepted for publication as a Regular Article in Physical Review D15

References in corpus (4)

• Mimicking Dark Energy with Lemaitre-Tolman-Bondi Models: Weak Central Singularities and Critical Points
• The supernova Hubble diagram for off-center observers in a spherically symmetric inhomogeneous universe
• Mapping Luminosity-Redshift Relationship to LTB Cosmology
• Cosmological Acceleration and Gravitational Collapse

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• CMB dipoles and other low-order multipoles in the quasispherical Szekeres model
• Noncommutative Corrections to the Robertson-Walker metric
• Cosmology With A Dark Refraction Index
• Fitting of supernovae without dark energy
• Apparent versus true value of the cosmological constant