An alternative to the cosmological 'concordance model'

By A. Blanchard, M. Douspis, M. Rowan‐Robinson, S. Sarkar. 2003

156 citations recorded by the source corpus.

Precision measurements of the cosmic microwave background by WMAP are believed to have established a flat $\Lambda$-dominated universe, seeded by nearly scale-invariant adiabatic primordial fluctuations. However by relaxing the hypothesis that the fluctuation spectrum can be described by a single power law, we demonstrate that an Einstein-de Sitter universe with {\em zero} cosmological constant can fit the data as well as the best concordance model. Moreover unlike a $\Lambda$-dominated universe, such an universe has no strong integrated Sachs-Wolfe effect, so is in better agreement with the low quadrupole seen by WMAP. The main problem is that the Hubble constant is required to be rather low: $H_0 \simeq 46$ km/s/Mpc; we discuss whether this can be consistent with observations. Furthermore for universes consisting only of baryons and cold dark matter, the amplitude of matter fluctuations on cluster scales is too high, a problem which seems generic. However, an additional small contribution ($\Omega_X \sim 0.1$) of matter which does not cluster on small scales, e.g. relic neutrinos with mass of order eV or a `quintessence' with $w \sim 0$, can alleviate this problem. Such models provide a satisfying description of the power spectrum derived from the 2dF galaxy redshift survey and from observations of the Ly-$\alpha$ forest. We conclude that Einstein-de Sitter models can indeed accommodate all data on the large scale structure of the Universe, hence the Hubble diagram of distant Type Ia supernovae remains the only {\em direct} evidence for a non-zero cosmological constant.

Subfields: Astronomy and Astrophysics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/caf1f5de883b02f579f9c5e96fb1085ae4a98822

How researchers see this paper

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In Astronomy and Astrophysics

1. T. Buchert
2. S. Rasanen
3. K. Enqvist
4. F. Tavecchio
5. Teppo Mattsson
6. L. Maraschi
7. G. Bonnoli
8. C. Baugh

In Statistical and Nonlinear Physics

1. Teppo Mattsson
2. K. Enqvist
3. S. Rasanen
4. G. Huetsi
5. C. Baugh
6. U. Padova
7. Y. Wong
8. Francisco Prada

Citations in the corpus

• Neutrino Mass in Cosmology: Status and Prospects (2011, methodology): “The model of [50], although incompatible with BAO and SN,”
• A primer on hierarchical galaxy formation: the semi-analytical approach (2006, background): “Blanchard et al. (2003) present a model without dark energy that can reproduce the CMB and galaxy power spectrum data, albeit with an uncomfortably low value for the Hubble constant, thus leaving only the supernova observations as evidence in favour of cosmological constant.”
• Optimized dark matter searches in deep observations of Segue 1 with MAGIC (2013, methodology): “Other non-standard cosmological models include the Gödel Universe [32], the Quasi-Steady state cosmology [33], the Brans-Dickie cosmology [34], the Einstein-de Sitter Universe [35], etc.”
• Accelerated expansion from structure formation (2006, background): “a global model with no acceleration can fit most other observations, including the CMB and LSS [27] (though it is not supported by studies of the local and global expansion rate [28]).”
• Dark Energy from structure: a status report (2007, background): “about 1/4 of the total source of Friedmann’s equations, up to a few percent that have to be attributed to baryonic matter and neutrinos (in the matter–dominated era). There are, however, other voices [19], [18]. Contemporary research to uncover this enigma pursues essentially two directions: one foc”
• Acoustic oscillations in the SDSS DR4 luminous red galaxy sample power spectrum (2005, background): “In Blanchard et al. (2003) it has been shown that it is possible to fit a large body of observational data with an Einstein–de Sitt r type model if one adopts low value for the Hubble parameter and relaxes the usual assumptions about the single power law initial spectrum.”
• The effect of inhomogeneous expansion on the supernova observations (2006, methodology): “uioui and Grøn have realized this in practice by fitting the LTB model to the first peak of the CMB [26]. It has also been argued that even the homogeneous model can fit the CMB data without dark energy [40]. Our another focus was on the averaged dynamics of the dust universe, given by the Buchert equa”
• Dark energy from backreaction (2003, unknown): “-k”