Constraints on growth index parameters from current and future observations

Dossett, Jason; Ishak, Mustapha; Moldenhauer, Jacob; Gong, Yungui; Wang, Anzhong

doi:10.1088/1475-7516/2010/04/022

Cited by 50 publications

(59 citation statements)

References 70 publications

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“…It has been noted that in General Relativity the slope is positive [23,36,37]. For all clustering dark energy models that we have considered, the slope for the growth index is positive, γ b > 0 (see table II).…”

Section: Growth Indexmentioning

confidence: 78%

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Impact of dark energy perturbations on the growth index

Batista

2014

Phys. Rev. D

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We show that in clustering dark energy models the growth index of linear matter perturbations, γ, can be much lower than in ΛCDM or smooth quintessence models and presents a strong variation with redshift. We find that the impact of dark energy perturbations on γ is enhanced if the dark energy equation of state has a large and rapid decay at low redshift. We study four different models with these features and show that we may have 0.33 < γ (z) < 0.48 at 0 < z < 3. We also show that the constant γ parametrization for the growth rate, f = d ln δm/d ln a = Ω γ m , is a few percent inaccurate for such models and that a redshift dependent parametrization for γ can provide about four times more accurate fits for f . We discuss the robustness of the growth index to distinguish between General Relativity with clustering dark energy and modified gravity models, finding that some f (R) and clustering dark energy models can present similar values for γ.

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Section: Growth Indexmentioning

confidence: 78%

“…We observe that the constant γ 0 parametrizations for models A and C present errors about 2%, but reaching almost 6% for models B and D at very low z. Given this inaccuracy of the constant γ 0 parametrization in the clustering models, we also study the following redshift dependent parametrization for γ [36]:…”

Section: Growth Indexmentioning

confidence: 96%

Impact of dark energy perturbations on the growth index

Batista

2014

Phys. Rev. D

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“…It has been shown recently [54] that the parametrization smoothly interpolates a low and intermediate redshift range to a high redshift range up to the cosmic microwave background scale. The above parametrization is also taken up in different contexts [55]. In this paper we parametrize γ in terms of MCG parameters namely, A s , α and B.…”

Section: Parametrization Of the Growth Indexmentioning

confidence: 99%

Observational constraints on modified Chaplygin gas from cosmic growth

Paul

Thakur²

2013

J. Cosmol. Astropart. Phys.

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Abstract. We investigate the linear growth function for the large scale structures of the universe considering modified Chaplygin gas as dark energy. Taking into account observational growth data for a given range of redshift from the Wiggle-Z measurements and rms mass fluctuations from Ly-α measurements we numerically analyze cosmological models to constrain the parameters of the MCG. The observational data of Hubble parameter with redshift (Z) is also considered. The Wang-Steinhardt ansatz for growth index γ and growth function f (defined as f = Ω γ m (a)) are considered for the numerical analysis. The best-fit values of the equation of state parameters obtained here is employed to study the growth function (f ), growth index (γ) and state parameter (ω) with redshift z. We note that MCG satisfactorily accommodates an accelerating phase followed by a matter dominated universe.

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“…(41). This result was attained by considering at late times in GR the potentials in (38) can be written combining to (2) and (3) as…”

Section: Isw-galaxy Cross Correlations Implementationmentioning

confidence: 99%

Testing general relativity at cosmological scales: Implementation and parameter correlations

2011

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The testing of general relativity at cosmological scales has become a possible and timely endeavor that is not only motivated by the pressing question of cosmic acceleration but also by the proposals of some extensions to general relativity that would manifest themselves at large scales of distance. We analyze here correlations between modified gravity growth parameters and some core cosmological parameters using the latest cosmological data sets including the refined Cosmic Evolution Survey 3D weak lensing. We provide the parametrized modified growth equations and their evolution. We implement known functional and binning approaches, and propose a new hybrid approach to evolve the modified gravity parameters in redshift (time) and scale. The hybrid parametrization combines a binned redshift dependence and a smooth evolution in scale avoiding a jump in the matter power spectrum. The formalism developed to test the consistency of current and future data with general relativity is implemented in a package that we make publicly available and call ISiTGR (Integrated Software in Testing General Relativity), an integrated set of modified modules for the publicly available packages CosmoMC and CAMB, including a modified version of the integrated SachsWolfe-galaxy cross correlation module of Ho et al and a new weak-lensing likelihood module for the refined Hubble Space Telescope Cosmic Evolution Survey weak gravitational lensing tomography data. We obtain parameter constraints and correlation coefficients finding that modified gravity parameters are significantly correlated with σ8 and mildly correlated with Ωm, for all evolution methods. The degeneracies between σ8 and modified gravity parameters are found to be substantial for the functional form and also for some specific bins in the hybrid and binned methods indicating that these degeneracies will need to be taken into consideration when using future high precision data.PACS numbers: 95.36.+x,98.80.Es,98.62.Sb

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Constraints on growth index parameters from current and future observations

Cited by 50 publications

References 70 publications

Impact of dark energy perturbations on the growth index

Impact of dark energy perturbations on the growth index

Observational constraints on modified Chaplygin gas from cosmic growth

Testing general relativity at cosmological scales: Implementation and parameter correlations

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