Keynésiens et/ou sociaux-libéraux ?

Taddéi, Dominique

doi:10.3917/leco.011.0062

Cited by 6 publications

(12 citation statements)

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“…where for the latter equality we have set σ 8 (z) = σ 8 D(z), Ω m (z) = Ω m0 (1 + z) 3 /E 2 (z), D(z) is the growth factor normalized to unity at the present time and γ(z) is the growth index. Now, we provide the basic steps towards marginalizing χ 2 gr over σ 8 (see also [78]). Substituting the second equality Eq.…”

Section: A Analysis With the Real Datamentioning

confidence: 99%

Testing Einstein’s gravity and dark energy with growth of matter perturbations: Indications for new physics?

Basilakos

Nesseris

2016

Phys. Rev. D

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The growth index of matter fluctuations is computed for ten distinct accelerating cosmological models and confronted to the latest growth rate data via a two-step process. First, we implement a joint statistical analysis in order to place constraints on the free parameters of all models using solely background data. Second, using the observed growth rate of clustering from various galaxy surveys we test the performance of the current cosmological models at the perturbation level while either marginalizing over σ8 or having it as a free parameter. As a result, we find that at a statistical level, i.e. after considering the best-fit χ 2 or the value of the Akaike information criterion, most models are in very good agreement with the growth rate data and are practically indistinguishable from ΛCDM. However, when we also consider the internal consistency of the models by comparing the theoretically predicted values of (γ0, γ1), i.e. the value of the growth index γ(z) and its derivative today, with the best-fit ones, we find that the predictions of three out of ten dark energy models are in mild tension with the best-fit ones when σ8 is marginalized over. When σ8 is free we find that most models are not only in mild tension, but also predict low values for σ8. This could be attributed to either a systematic problem with the growth-rate data or the emergence of new physics at low redshifts, with the latter possibly being related to the well-known issue of the lack of power at small scales. Finally, by utilizing mock data based on an LSST-like survey we show that with future surveys and by using the growth index parameterization, it will be possible to resolve the issue of the low σ8 but also the tension between the fitted and theoretically predicted values of (γ0, γ1).PACS numbers: 95.36.+x, 04.50.Kd, 98.80.Es

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Section: A Analysis With the Real Datamentioning

confidence: 99%

Testing Einstein’s gravity and dark energy with growth of matter perturbations: Indications for new physics?

Basilakos

Nesseris

2016

Phys. Rev. D

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“…(25) we need four independent observables: the Hubble parameter HðzÞ, the fσ 8 ðzÞ, σ 8 ðz ¼ 0Þ, and Ω m 0 h 2 . To be more specific, we use the fσ 8 data from different experiments and collected by Refs [38,39], and we reported them in Table I, and the Hubble parameters values measured from passively evolving galaxies data given in Moresco et al [40] and the values of the Hubble parameters using radial BAO from different experiments [41,42] and [43]; we report the values in Table II.…”

Section: A Binning the Datamentioning

confidence: 99%

Reconstruction of the null-test for the matter density perturbations

2015

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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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“…Similar analysis has been proposed by Taddei & Amendola [36] and Basilakos & Nesseris [37]) in order to marginalize chi-square function of the growth rate data over the value of the rms fluctuations at 8h −1 Mpc, namely σ 8 .…”

Section: Statistical Analysis With H(z) Datamentioning

confidence: 81%

Constraining the dark energy models with H(z) data: An approach independent of H0

Anagnostopoulos

Basilakos

2018

Phys. Rev. D

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We study the performance of the latest H(z) data in constraining the cosmological parameters of different cosmological models, including that of Chevalier-Polarski-Linder w0w1 parametrization. First, we introduce a statistical procedure in which the chi-square estimator is not affected by the value of the Hubble constant. As a result, we find that the H(z) data do not rule out the possibility of either non-flat models or dynamical dark energy cosmological models. However, we verify that the time varying equation-of-state parameter w(z) is not constrained by the current expansion data. Combining the H(z) and the Type Ia supernova data we find that the H(z)/SNIa overall statistical analysis provides a substantial improvement of the cosmological constraints with respect to those of the H(z) analysis. Moreover, the w0 − w1 parameter space provided by the H(z)/SNIa joint analysis is in a very good agreement with that of Planck 2015, which confirms that the present analysis with the H(z) and SNIa probes correctly reveals the expansion of the Universe as found by the team of Planck. Finally, we generate sets of Monte Carlo realizations in order to quantify the ability of the H(z) data to provide strong constraints on the dark energy model parameters. The Monte Carlo approach shows significant improvement of the constraints, when increasing the sample to 100 H(z) measurements. Such a goal can be achieved in the future, especially in the light of the next generation of surveys. PACS numbers: 95.36.+x, 04.50.Kd, 98.80.Es

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Keynésiens et/ou sociaux-libéraux ?

Cited by 6 publications

References 0 publications

Testing Einstein’s gravity and dark energy with growth of matter perturbations: Indications for new physics?

Testing Einstein’s gravity and dark energy with growth of matter perturbations: Indications for new physics?

Reconstruction of the null-test for the matter density perturbations

Constraining the dark energy models with H(z) data: An approach independent of H0

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