Constraining teleparallel gravity through Gaussian processes

Abstract

We apply Gaussian processes (GP) in order to impose constraints on teleparallel gravity and its f(T) extensions. We use available H(z) observations from (i) cosmic chronometers data (CC); (ii) Supernova type Ia (SN) data from the compressed pantheon release together with the CANDELS and CLASH multi-cycle treasury programs; and (iii) baryonic acoustic oscillation (BAO) datasets from the sloan digital sky survey. For the involved covariance functions, we consider four widely used choices, namely the square exponential, Cauchy, Matérn and rational quadratic kernels, which are consistent with one another within 1σ confidence levels. Specifically, we use the GP approach to reconstruct a model-independent determination of the Hubble constant H 0, for each of these kernels and dataset combinations. These analyses are complemented with three recently announced literature values of H 0, namely (i) Riess H 0 R = 74.22 ± 1.82 k m s − 1 M p c − 1 ; (ii) H0LiCOW collaboration H 0 HW = 73 . 3 − 1.8 + 1.7 k m s − 1 M p c − 1 ; and (iii) Carnegie–Chicago Hubble programme H 0 TRGB = 69.8 ± 1.9 k m s − 1 M p c − 1 . Additionally, we investigate the transition redshift between the decelerating and accelerating cosmological phases through the GP reconstructed deceleration parameter. Furthermore, we reconstruct the model-independent evolution of the dark energy equation of state, and finally reconstruct the allowed f(T) functions. As a result, the ΛCDM model lies inside the allowed region at 1σ in all the examined kernels and datasets, however a negative slope for f(T) versus T is slightly favoured.

Improving data-driven model-independent reconstructions and updated constraints on dark energy models from Horndeski cosmology

“…To compare our model-independent reconstruction with other proposals in this direction, several methods have been presented in the literature to obtain reconstructions of the Hubble parameter [26][27][28]40]. Moreover, some of them present some disadvantages with respect to our methodology:…”

“…In comparison to our proposal in the SNIa/QSO cosmokinetic reconstruction method is not indicated the value of H 0 used to calibrate Pantheon data, therefore, a straightforward bias emerges as a consequence of this prior. [27]. In this research the main goal was to obtain constraints on Teleparallel Gravity models [18] through GP using CC data set, BAO data [15,45,46], and the Pantheon compressed data set [47] -statistics for the full data sets reconstructed Pantheon+ H0 + CC+ CL (first column) using the H0 priors for the squared exponential kernel (second column) and the Cauchy kernel (third column), using (16).…”

“…The covariance function expresses the fact that the function evaluated at one point z is not independent of the function evaluated at other point z, but rather these are correlated and the relationship is given by the covariance function. There is a wide range of possible covariance functions 1 , moreover it has been shown that the choice of a kernel does not significantly influence the derived value of the cosmological parameters to be determined by the reconstruction [26][27][28], i.e. even when the mean value of these parameters varies when we change the covariance function, these values coincide within 1-σ.…”

“…GP have been widely used in the literature for different purposes, ranging from the study of growth rate of structure f σ 8 (z) [31], to obtain constraints on Teleparallel gravity models [27], and even some authors have found a way to use the reconstructions to test the ΛCDM model, in [29] they use the reconstructions of H(z) to look for deviations from the equation of state of the cosmological constant Λ, in [32] they found a way to test the concordance model using a diagnostic function O m [32,33]. To proceed our reconstructions we require the following samples:…”

“…Furthermore, once we consider data from several surveys with have to deal with a problem of model-dependency according to the nature of these observations. This problem has motivated the study of other methods that extract important information directly from the observational data and obtain as much as possible the properties of the dynamics of the Hubble flow [25][26][27][28]. These kinds of approaches attempt to reconstruct the cosmological evolution directly from observations without establishing an association with a theoretical physical model.…”