Cosmic chronometers with photometry: a new path to H(z)

Jimenez, Raul; Moresco, Michele; Verde, Licia; Wandelt, Benjamin D.

doi:10.1088/1475-7516/2023/11/047

Cited by 6 publications

(1 citation statement)

References 30 publications

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“…It is important to emphasize that the set of CC measurements involve systematic uncertainties arising from several astrophysical factors, including the choice of initial mass function, stellar library, and metallicity. These systematic uncertainties are quantified in [57] (see also discussions in this regard in [58,59]). Understanding and addressing these sources of uncertainty is essential for accurate use in astrophysical studies.…”

Section: The H (Z) Datamentioning

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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Section: The H (Z) Datamentioning

confidence: 99%

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

Oliveira,

Avila,

Bernui

et al. 2024

Eur. Phys. J. C

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Beyond ΛCDM with f(z)CDM: Criticalities and solutions of Padé Cosmography

Petreca,

Benetti,

Capozziello

2024

Physics of the Dark Universe

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A stochastic approach to reconstructing the speed of light in cosmology

Zhang,

Hong,

Wang

et al. 2024

Monthly Notices of the Royal Astronomical Society

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The varying speed of light (VSL) model describes how the speed of light in a vacuum changes with cosmological redshift. Despite numerous models, there is little observational evidence for this variation. While the speed of light can be accurately measured by physical means, cosmological methods are rarely used. Previous studies quantified the speed of light at specific redshifts using Gaussian processes and reconstructed the redshift-dependent function $c(z)$. It is crucial to quantify the speed of light across varying redshifts. We use the latest data on angular diameter distances $D_\mathrm{ A}(z)$ and Hubble parameters $H(z)$ from baryon acoustic oscillation and cosmic chronometer measurements in the redshift interval $z\in [0.07,1.965]$. The speed of light $c(z)$ is determined using Gaussian and deep Gaussian processes to reconstruct $H(z)$, $D_\mathrm{ A}(z)$, and $D^{\prime }_\mathrm{ A}(z)$. Furthermore, we conduct comparisons across three distinct models, encompassing two renowned VSL models. We get the result of the parameters constraints in the models (1) for the ‘c-c’ model, $c_0=29\,492.6 \pm ^{6.2}_{5.3} \mathrm{~km} \mathrm{~s}^{-1}$. (2) For the ‘c-cl’ model, $c_0=29\,665.5 \pm ^{11.2}_{11.4}\mathrm{~km} \mathrm{~s}^{-1}$ and $n=0.05535 \pm\, ^{0.00008}_{0.00007}$. (3) For the ‘c-CPL’ model, $c_0=29\,555.7 \pm ^{13.3}_{13.2} \mathrm{~km} \mathrm{~s}^{-1}$ and $n=-0.0607 \pm 0.0001$. Based on our findings, it may be inferred that Barrow’s classical VSL model is not a suitable fit for our data. In contrast, the widely recognized Chevallier–Polarski–Linder (CPL) VSL model, under some circumstances, as well as the universal ‘c is constant’ model, demonstrate a satisfactory ability to account for our findings.

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Cosmic chronometers with photometry: a new path to H(z)

Cited by 6 publications

References 30 publications

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

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

Beyond ΛCDM with f(z)CDM: Criticalities and solutions of Padé Cosmography

A stochastic approach to reconstructing the speed of light in cosmology

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