Sweeping Horndeski canvas: new growth-rate parameterization for modified-gravity theories

Wen, Yuewei; Nguyen, Nhat-Minh; Huterer, Dragan

doi:10.1088/1475-7516/2023/09/028

Cited by 11 publications

(3 citation statements)

References 95 publications

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“…Despite the model being purely phenomenological, a measurement of γ inconsistent with its ΛCDM prediction would provide a clear detection of deviations from the standard cosmological model. On the other hand, it has been shown that the growth index parameterisation can provide a good fit for specific modified gravity models, such as the DGP model [37], with γ ≃ 0.67 [38,39], and a class of Horndeski theories [40], although in that case a time dependent growth index is required. For this reason a precise measurement of the growth index is among the objectives of forthcoming Stage-IV surveys [10,14,41].…”

Section: Jcap12(2023)025mentioning

confidence: 99%

“…(2.10) and (2.11) are then used to re-scale the linear power spectrum computed at redshift z = 0 and construct the redshift space multipoles as described in section 2.1. An analysis of the behaviour of γ over cosmic history can be found in [67,68], while [40] propose an alternative parameterisation, that extends γ to be a function of redshift.…”

Section: Jcap12(2023)025mentioning

confidence: 99%

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Modified gravity and massive neutrinos: constraints from the full shape analysis of BOSS galaxies and forecasts for Stage IV surveys

Moretti,

Tsedrik,

Carrilho

et al. 2023

J. Cosmol. Astropart. Phys.

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We constrain the growth index γ by performing a full-shape analysis of the power spectrum multipoles measured from the BOSS DR12 data. We adopt a theoretical model based on the Effective Field theory of the Large Scale Structure (EFTofLSS) and focus on two different cosmologies: γCDM and γνCDM, where we also vary the total neutrino mass. We explore different choices for the priors on the primordial amplitude As and spectral index ns , finding that informative priors are necessary to alleviate degeneracies between the parameters and avoid strong projection effects in the posterior distributions. Our tightest constraints are obtained with 3σ Planck priors on As and ns : we obtain γ = 0.647 ± 0.085 for γCDM and γ = 0.612+0.075 -0.090, Mν < 0.30 for γνCDM at 68% c.l., in both cases ∼ 1σ consistent with the ΛCDM prediction γ ≃ 0.55. Additionally, we produce forecasts for a Stage-IV spectroscopic galaxy survey, focusing on a DESI-like sample. We fit synthetic data-vectors for three different galaxy samples generated at three different redshift bins, both individually and jointly. Focusing on the constraining power of the Large Scale Structure alone, we find that forthcoming data can give an improvement of up to ∼ 85% in the measurement of γ with respect to the BOSS dataset when no CMB priors are imposed. On the other hand, we find the neutrino mass constraints to be only marginally better than the current ones, with future data able to put an upper limit of Mν < 0.27 eV. This result can be improved with the inclusion of Planck priors on the primordial parameters, which yield Mν < 0.18 eV.

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Section: Jcap12(2023)025mentioning

confidence: 99%

Section: Jcap12(2023)025mentioning

confidence: 99%

Modified gravity and massive neutrinos: constraints from the full shape analysis of BOSS galaxies and forecasts for Stage IV surveys

Moretti,

Tsedrik,

Carrilho

et al. 2023

J. Cosmol. Astropart. Phys.

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“…Therefore, one can probe the CDM model by measuring the growth index γ , because it has potential to distinguish GR and modified gravity models [21,[25][26][27][28]. In fact, a possible evidence for the growth index evolution and its cosmological implications has been recently discussed [29][30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Reconstructing the growth index $$\gamma $$ with Gaussian processes

Oliveira,

Avila,

Bernui

et al. 2024

Eur. Phys. J. C

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Alternative cosmological models have been proposed to alleviate the tensions reported in the concordance cosmological model, or to explain the current accelerated phase of the universe. One way to distinguish between General Relativity and modified gravity models is using current astronomical data to measure the growth index $$\gamma $$ γ , a parameter related to the growth of matter perturbations, which behaves differently in different metric theories. We propose a model independent methodology for determining $$\gamma $$ γ , where our analyses combine diverse cosmological data sets, namely $$\{ f(z_i) \}$$ { f ( z i ) } , $$\{ [f\sigma _8](z_i) \}$$ { [ f σ 8 ] ( z i ) } , and $$\{ H(z_i) \}$$ { H ( z i ) } , and use Gaussian Processes, a non-parametric approach suitable to reconstruct functions. This methodology is a new consistency test for $$\gamma $$ γ constant. Our results show that, for the redshift interval $$0< z < 1$$ 0 < z < 1 , $$\gamma $$ γ is consistent with the constant value $$\gamma = 0.55$$ γ = 0.55 , expected in General Relativity theory, within $$2 \sigma $$ 2 σ confidence level (CL). Moreover, we find $$\gamma (z=0)$$ γ ( z = 0 ) = 0.311 $$\pm 0.144 $$ ± 0.144 and $$\gamma (z=0) = 0.609 \pm 0.200$$ γ ( z = 0 ) = 0.609 ± 0.200 for the reconstructions using the $$\{ f(z_i) \}$$ { f ( z i ) } and $$\{ [f\sigma _8](z_i) \}$$ { [ f σ 8 ] ( z i ) } data sets, respectively, values that also agree at a 2$$\sigma $$ σ CL with $$\gamma = 0.55$$ γ = 0.55 . Our methodology and analyses can be considered as an alternative approach in light of the current discussion in the literature that suggests a possible evidence for the growth index evolution.

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A trium test on beyond ΛCDM triggering parameters

Sakr

2023

J. Cosmol. Astropart. Phys.

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We performed a Bayesian study on three beyond ΛCDM phenomenological triggering parameters, the growth index γ, the dark energy equation of state parameter ω and the lensing deviation from the GR prediction parameter Σ, using the latest cosmological geometric, growth and lensing probes, all in a consistent implementation within the modified gravity cosmological solver code MGCLASS. We find, when we combined all our probes, i.e. the cosmic microwave background (CMB), the baryonic acoustic oscilation (BAO), the growth measurements fσ 8 and the 3×2pt joint analysis of weak lensing and galaxy clustering in photometric redshift surveys, assuming flat space, constraints compatible with general relativity and ΛCDM with ω = -1.025 ± 0.045, and Σ = 0.992 ± 0.022 at the 68% level, while γ = 0.633±0.044 is still within ∼ 2σ from the ΛCDM value of γ ∼ 0.55, and that when Σ is considered as constant; while γℓ = -0.025 ±0.045 when the lensing parameter is parameterised as function of a lensing index, introduced for the first time in this work, as Σ(z) = Ωm(z)γℓ .

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Sweeping Horndeski canvas: new growth-rate parameterization for modified-gravity theories

Cited by 11 publications

References 95 publications

Modified gravity and massive neutrinos: constraints from the full shape analysis of BOSS galaxies and forecasts for Stage IV surveys

Modified gravity and massive neutrinos: constraints from the full shape analysis of BOSS galaxies and forecasts for Stage IV surveys

Reconstructing the growth index $$\gamma $$ with Gaussian processes

A trium test on beyond ΛCDM triggering parameters

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