Fingerprinting dark energy

Sapone, Domenico; Kunz, M.

doi:10.1103/physrevd.80.083519

Cited by 78 publications

(158 citation statements)

References 31 publications

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“…However, one may easily check that the latter system contains a particular solution, namely δ de = (1 + w)δm (see also Bean & Dore 2004;Abramo et al 2007;Ballesteros & Riotto 2008;Abramo et al 2009). Also, analytical solutions under of specific conditions can be found in Sapone & Kunz (2009) and Sapone & Majerotto (2012). Note that the accelerated expansion of the universe poses the restriction w < −1/3Ω de0 which implies ∆ de < (3Ω de0 − 1)/3Ω de0 .…”

Section: Dark Energy Perturbations and The Growth Indexmentioning

confidence: 99%

The growth index of matter perturbations using the clustering of dark energy

Basilakos

2015

Monthly Notices of the Royal Astronomical Society

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We have put forward a new unified framework which provides a consistent and rather complete account of the growth index of matter perturbations in the regime where the dark energy is allowed to have clustering. In particular, we find that the growth index is not only affected by the cosmological parameters but rather it depends on the choice of the considered dark energy (homogeneous or clustered). Using the Planck priors and performing a standard χ 2 -minimization between theoretical expectations and growth data, we statistically quantify the ability of the growth index to represent the observations. Finally, based on the growth index analysis we find that the growth data favor the clustered dark energy scenario.

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Section: Dark Energy Perturbations and The Growth Indexmentioning

confidence: 99%

The growth index of matter perturbations using the clustering of dark energy

Basilakos

2015

Monthly Notices of the Royal Astronomical Society

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“…We find that the limits on w do not change from the quintessence case and that there is no significant constraint on the DE speed of sound using current data. This can be understood as follows: on scales larger than the sound horizon and for w close to −1, DE perturbations are related to dark matter perturbations through ∆ DE (1 + w)∆ m /4 and inside the sound horizon they stop growing because of pressure support (see e.g., Creminelli et al 2009;Sapone & Kunz 2009). In addition, at early times the DE density is much smaller than the matter density, with…”

Section: Minimally Coupled De: Sound Speed and K-essencementioning

confidence: 99%

Planck2015 results

Ade

Aghanim

Arnaud

et al. 2016

A&A

605

266

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We study the implications of Planck data for models of dark energy (DE) and modified gravity (MG) beyond the standard cosmological constant scenario. We start with cases where the DE only directly affects the background evolution, considering Taylor expansions of the equation of state w(a), as well as principal component analysis and parameterizations related to the potential of a minimally coupled DE scalar field. When estimating the density of DE at early times, we significantly improve present constraints and find that it has to be below ∼2% (at 95% confidence) of the critical density, even when forced to play a role for z < 50 only. We then move to general parameterizations of the DE or MG perturbations that encompass both effective field theories and the phenomenology of gravitational potentials in MG models. Lastly, we test a range of specific models, such as k-essence, f (R) theories, and coupled DE. In addition to the latest Planck data, for our main analyses, we use background constraints from baryonic acoustic oscillations, type-Ia supernovae, and local measurements of the Hubble constant. We further show the impact of measurements of the cosmological perturbations, such as redshift-space distortions and weak gravitational lensing. These additional probes are important tools for testing MG models and for breaking degeneracies that are still present in the combination of Planck and background data sets. All results that include only background parameterizations (expansion of the equation of state, early DE, general potentials in minimally-coupled scalar fields or principal component analysis) are in agreement with ΛCDM. When testing models that also change perturbations (even when the background is fixed to ΛCDM), some tensions appear in a few scenarios: the maximum one found is ∼2σ for Planck TT+lowP when parameterizing observables related to the gravitational potentials with a chosen time dependence; the tension increases to, at most, 3σ when external data sets are included. It however disappears when including CMB lensing.

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“…Equation (29) describes the amount of the dark energy perturbations and it has been evaluated under the assumption of zero dark energy sound speed and zero anisotropic stress, [7]. If we set w ¼ −1 then we recover the ΛCDM model, i.e., with zero perturbations.…”

Section: A Wcdm Modelmentioning

confidence: 99%

“…The scale at which this dark energy component can cluster depends on the intrinsic characteristic of the fluid itself, namely, pressure perturbations δp that are related to the sound speed and anisotropic stress σ that is usually related to the viscosity of the fluid (see [7][8][9][10]). If dark energy is able to cluster at sufficiently small scales then Eq.…”

Section: A Wcdm Modelmentioning

confidence: 99%

“…In the latter, we introduced a new null-test specifically for the growth of matter perturbations and, as far as we know, this is the first null-test that accounts for perturbations on the matter fluids. The evolution of the matter density contrast is governed by the evolution of the Hubble parameter and by the evolution of all the other clustering components [7][8][9][10]. Hence, it is a complementary probe for the dark energy because, while many different dark energy models give the same expansion history they usually differ at perturbation level (depending on the intrinsic characteristics of the fluid itself) and they will affect the evolution of the matter density contrast.…”

Section: Introductionmentioning

confidence: 99%

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Reconstruction of the null-test for the matter density perturbations

2015

Self Cite

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We systematically study the null-test for the growth rate data first presented in [S. Nesseris and D. Sapone, arXiv:1409.3697.] and we reconstruct it using various combinations of data sets, such as the fσ 8 and HðzÞ or type Ia supernovae data. We perform the reconstruction in two different ways, either by directly binning thedata or by fitting various dark energy models. We also examine how well the null-test can be reconstructed by future data by creating mock catalogs based on the cosmological constant model, a model with strong dark energy perturbations, the fðRÞ and fðGÞ models, and the large void LemaitreTolman-Bondi model that exhibit different evolution of the matter perturbations. We find that with future data similar to an LSST-like survey, the null-test will be able to successfully discriminate between these different cases at the 5σ level.

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Fingerprinting dark energy

Cited by 78 publications

References 31 publications

The growth index of matter perturbations using the clustering of dark energy

The growth index of matter perturbations using the clustering of dark energy

Planck2015 results

Reconstruction of the null-test for the matter density perturbations

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