Non-linear structure formation in cosmologies   with early dark
 energy

Bartelmann, Matthias; Doran, Michael; Wetterich, C.

doi:10.1051/0004-6361:20053922

Cited by 97 publications

(180 citation statements)

References 56 publications

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“…Methods to measure the linear bias, while present, are not as reliable as the shape of the power spectrum, as they involve nonlinear physics, and thus are not widely used to obtain cosmological constraints. In addition, analytic calculations of non-linear structure formation in similar model of early dark energy yield considerable and quite unexpected deviations from the ΛCDM scenario precluding the use of standard approximations to infer the non-linear spectrum given the linear evolution [23]. Thus, instead of galaxy catalogs, we use Lyman-α forest observations of quasar spectra from the Sloan Digital Sky Survey (SDSS) [5], which mainly constrains the linear overdensity ∆ 2 L and spectral index n eff at a pivot scale of k ≃ 0.009 s/km (≃ 1 Mpc −1 ), and a pivot redshift of z ≃ 3 [5].…”

Section: B Quadratic (Tracking) Potentialmentioning

confidence: 99%

Cuscuton cosmology: Dark energy meets modified gravity

et al. 2007

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In a companion paper [1], we have introduced a model of scalar field dark energy, Cuscuton, which can be realized as the incompressible (or infinite speed of sound) limit of a k-essence fluid. In this paper, we study how Cuscuton modifies the constraint sector of Einstein gravity. In particular, we study Cuscuton cosmology and show that even though Cuscuton can have an arbitrary equation of state, or time dependence, and is thus inhomogeneous, its perturbations do not introduce any additional dynamical degree of freedom and only satisfy a constraint equation, amounting to an effective modification of gravity on large scales. Therefore, Cuscuton can be considered to be a minimal theory of evolving dark energy, or a minimal modification of a cosmological constant, as it has no internal dynamics. Moreover, this is the only modification of Einstein gravity to our knowledge, that does not introduce any additional degrees freedom (and is not conformally equivalent to the Einstein gravity). We then study two simple Cuscuton models, with quadratic and exponential potentials. The quadratic model has the exact same expansion history as ΛCDM, and yet contains an early dark energy component with constant energy fraction, which is constrained to ΩQ < ∼ 2%, mainly from WMAP Cosmic Microwave Background (CMB) and SDSS Lyman-α forest observations. The exponential model has the same expansion history as the DGP self-accelerating braneworld model, but generates a much smaller integrated Sachs-Wolfe (ISW) effect, and is thus consistent with the CMB observations. Finally, we show that the evolution is local on super-horizon scales, implying that there is no gross violation of causality, despite Cuscuton's infinite speed of sound.

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Section: B Quadratic (Tracking) Potentialmentioning

confidence: 99%

Cuscuton cosmology: Dark energy meets modified gravity

et al. 2007

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“…Figure 19 shows an example of SZ angular power spectra for the galaxy cluster contribution, demonstrating that the non-Gaussian χ 2 m model can have a substantial impact for 10 3 < ℓ < 10 4 , especially in the case of WMAP-3 yrs normalisation (σ 8 = 0.74). Also shown are examples of Gaussian models with different normalisations (σ 8 = 0.74, 0.8) and an early dark energy model (Bartelmann, Doran & Wetterich 2006).…”

Section: High-order Statistics Of Secondary Anisotropiesmentioning

confidence: 99%

Secondary anisotropies of the CMB

Aghanim¹,

Majumdar²,

Silk³

2008

Rep. Prog. Phys.

104

101

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Abstract.The Cosmic Microwave Background fluctuations provide a powerful probe of the dark ages of the universe through the imprint of the secondary anisotropies associated with the reionisation of the universe and the growth of structure. We review the relation between the secondary anisotropies and and the primary anisotropies that are directly generated by quantum fluctuations in the very early universe. The physics of secondary fluctuations is described, with emphasis on the ionisation history and the evolution of structure. We discuss the different signatures arising from the secondary effects in terms of their induced temperature fluctuations, polarisation and statistics. The secondary anisotropies are being actively pursued at present, and we review the future and current observational status.

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“…Considerably steeper slopes and lower normalization of the M-T relation are needed to reconcile the predicted mass functions of clusters with the observed XTF in this case. Alternative explanations that retain a low normalization of appeal to the effects of primordial j 8 non-Gaussianity (Sadeh et al 2006) or to dynamical dark energy (Bartelmann et al 2006). However, for the standard cosmological model, X-ray clusters of galaxies seem to prefer a higher than predicted by the CMB anisotropies, in agreement j 8 with the abundance of optical clusters from SDSS (Rines et al 2007;Rozo et al 2007).…”

mentioning

confidence: 94%

Is WMAP3 Normalization Compatible with the X-Ray Cluster Abundance?

Yepes

Sevilla

Gottlöber

et al. 2007

ApJ

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We present the mass and X-ray temperature functions derived from a sample of more than 15,000 galaxy clusters of the MareNostrum Universe cosmological SPH simulations. In these simulations, we follow structure formation in a cubic volume of Mpc on a side assuming cosmological parameters consistent with either Ϫ1 500 h the first-or third-year WMAP data and Gaussian initial conditions. We compare our numerical predictions with the most recent observational estimates of the cluster X-ray temperature functions and find that the low-normalization cosmological model inferred from the 3 year WMAP data results is barely compatible with the presentepoch X-ray cluster abundances. We can only reconcile the simulations with the observational data if we assume a normalization of the mass-temperature relation, which is a factor of ∼2.5-3 smaller than our nonradiative simulations predict. This deviation seems to be too large to be accounted by the effects of star formation or cooling in the ICM, which are not taken into account in these simulations.

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Non-linear structure formation in cosmologies with early dark energy

Cited by 97 publications

References 56 publications

Cuscuton cosmology: Dark energy meets modified gravity

Cuscuton cosmology: Dark energy meets modified gravity

Secondary anisotropies of the CMB

Is WMAP3 Normalization Compatible with the X-Ray Cluster Abundance?

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