Observational constraints on inhomogeneous cosmological models without dark energy

Marra, Valerio; Notari, Alessio

doi:10.1088/0264-9381/28/16/164004

Cited by 114 publications

(136 citation statements)

References 139 publications

(363 reference statements)

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“…This uncertainty inspired many to study inhomogeneous cosmologies (see Marra & Notari 2011;Bolejko et al 2011, for comprehensive reviews), including non-Copernican models that explain the apparent accelerated expansion of the Universe by means of radial inhomogeneities without requiring any form of dark energy. The basic idea behind these alternative models is quite simple because we know from observations and numerical simulations that the large-scale structure of the Universe consists of filaments and voids (see e.g.…”

Section: Introductionmentioning

confidence: 99%

“…The vast literature on inhomogeneous cosmologies -in particular LTB models -is summarised in the review articles by Bolejko et al (2011) and Marra & Notari (2011), which allows us to only focus on the aspects that are particularly relevant for this work. For reasons to be clarified later, we only discuss LTB models with synchronous Big Bang throughout, meaning that the bang time function is constant and the Universe has the same global age everywhere.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Probing spatial homogeneity with LTB models: a detailed discussion

Redlich

Bolejko

Meyer

et al. 2014

A&A

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Do current observational data confirm the assumptions of the cosmological principle, or is there statistical evidence for deviations from spatial homogeneity on large scales? To address these questions, we developed a flexible framework based on spherically symmetric, but radially inhomogeneous Lemaître-Tolman-Bondi (LTB) models with synchronous Big Bang. We expanded the (local) matter density profile in terms of flexible interpolation schemes and orthonormal polynomials. A Monte Carlo technique in combination with recent observational data was used to systematically vary the shape of these profiles. In the first part of this article, we reconsider giant LTB voids without dark energy to investigate whether extremely fine-tuned mass profiles can reconcile these models with current data. While the local Hubble rate and supernovae can easily be fitted without dark energy, however, model-independent constraints from the Planck 2013 data require an unrealistically low local Hubble rate, which is strongly inconsistent with the observed value; this result agrees well with previous studies. In the second part, we explain why it seems natural to extend our framework by a non-zero cosmological constant, which then allows us to perform general tests of the cosmological principle. Moreover, these extended models facilitate explorating whether fluctuations in the local matter density profile might potentially alleviate the tension between local and global measurements of the Hubble rate, as derived from Cepheid-calibrated type Ia supernovae and CMB experiments, respectively. We show that current data provide no evidence for deviations from spatial homogeneity on large scales. More accurate constraints are required to ultimately confirm the validity of the cosmological principle, however.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Probing spatial homogeneity with LTB models: a detailed discussion

Redlich

Bolejko

Meyer

et al. 2014

A&A

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“…where L geo , L geo ⊥ are given by (5). Our results show that the geometric formulas commonly used for constraining LTB with BAO fail at the percent level.…”

Section: A Computation Of the Correlation Functions And Extraction Omentioning

confidence: 82%

Galaxy correlations and the BAO in a void universe: structure formation as a test of the Copernican Principle

February

Clarkson

Maartens

2013

J. Cosmol. Astropart. Phys.

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A suggested solution to the dark energy problem is the void model, where accelerated expansion is replaced by Hubble-scale inhomogeneity. In these models, density perturbations grow on a radially inhomogeneous background. This large scale inhomogeneity distorts the spherical Baryon Acoustic Oscillation feature into an ellipsoid which implies that the bump in the galaxy correlation function occurs at different scales in the radial and transverse correlation functions. We compute these for the first time, under the approximation that curvature gradients do not couple the scalar modes to vector and tensor modes. The radial and transverse correlation functions are very different from those of the concordance model, even when the models have the same average BAO scale. This implies that if void models are fine-tuned to satisfy average BAO data, there is enough extra information in the correlation functions to distinguish a void model from the concordance model. We expect these new features to remain when the full perturbation equations are solved, which means that the radial and transverse galaxy correlation functions can be used as a powerful test of the Copernican Principle.

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“…There exists a large body of literature on cosmological models relying on the LTB dynamics, see, e.g., [22][23][24][25][26][27][28][29][30]. Our interest here is not primarily whether or not these inhomogeneous models can provide viable alternatives to the standard ΛCDM model.…”

Section: Lemaître-tolman-bondi (Ltb) Dynamicsmentioning

confidence: 99%

Averaged Lemaître–Tolman–Bondi dynamics

Isidro¹,

Barbosa²,

Piattella³

et al. 2016

Class. Quantum Grav.

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We consider cosmological backreaction effects in Buchert's averaging formalism on the basis of an explicit solution of the Lemaître-Tolman-Bondi (LTB) dynamics which is linear in the LTB curvature parameter and has an inhomogeneous bang time. The volume Hubble rate is found in terms of the volume scale factor which represents a derivation of the simplest phenomenological solution of Buchert's equations in which the fractional densities corresponding to average curvature and kinematic backreaction are explicitly determined by the parameters of the underlying LTB solution at the boundary of the averaging volume. This configuration represents an exactly solvable toy model but it does not adequately describe our "real" Universe. *

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Observational constraints on inhomogeneous cosmological models without dark energy

Cited by 114 publications

References 139 publications

Probing spatial homogeneity with LTB models: a detailed discussion

Probing spatial homogeneity with LTB models: a detailed discussion

Galaxy correlations and the BAO in a void universe: structure formation as a test of the Copernican Principle

Averaged Lemaître–Tolman–Bondi dynamics

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