On the Evolution of the Hubble Constant with the SNe Ia Pantheon Sample and Baryon Acoustic Oscillations: A Feasibility Study for GRB-Cosmology in 2030

Abstract

The difference from 4 to 6 σ in the Hubble constant (H0) between the values observed with the local (Cepheids and Supernovae Ia, SNe Ia) and the high-z probes (Cosmic Microwave Background obtained by the Planck data) still challenges the astrophysics and cosmology community. Previous analysis has shown that there is an evolution in the Hubble constant that scales as f(z)=H0/(1+z)η, where H0 is H0(z=0) and η is the evolutionary parameter. Here, we investigate if this evolution still holds by using the SNe Ia gathered in the Pantheon sample and the Baryon Acoustic Oscillations. We assume H0=70kms−1Mpc−1 as the local value and divide the Pantheon into three bins ordered in increasing values of redshift. Similar to our previous analysis but varying two cosmological parameters contemporaneously (H0, Ω0m in the ΛCDM model and H0, wa in the w0waCDM model), for each bin we implement a Markov-Chain Monte Carlo analysis (MCMC) obtaining the value of H0 assuming Gaussian priors to restrict the parameters spaces to values we expect from our prior knowledge of the current cosmological models and to avoid phantom Dark Energy models with w<−1. Subsequently, the values of H0 are fitted with the model f(z). Our results show that a decreasing trend with η∼10−2 is still visible in this sample. The η coefficient reaches zero in 2.0 σ for the ΛCDM model up to 5.8 σ for w0waCDM model. This trend, if not due to statistical fluctuations, could be explained through a hidden astrophysical bias, such as the effect of stretch evolution, or it requires new theoretical models, a possible proposition is the modified gravity theories, f(R). This analysis is meant to further cast light on the evolution of H0 and it does not specifically focus on constraining the other parameters. This work is also a preparatory to understand how the combined probes still show an evolution of the H0 by redshift and what is the current status of simulations on GRB cosmology to obtain the uncertainties on the Ω0m comparable with the ones achieved through SNe Ia.

Gaussian processes and effective field theory of $f(T)$ gravity under the $H_0$ tension

“…This tension suggests possible deviation from the standard ΛCDM cosmological model, inspiring people to explore the physical reasons behind this phenomenon. In particular, since the new data show greater tension, this issue has again aroused a lot of attention and research [10][11][12][13][14][15][16][17][18][19][20][21][22][23].…”

Running Hubble constant from the SNe Ia Pantheon sample?

“…to account for H 0 (z) in Eq. (10). These concepts suggest that an extra degree of freedom with respect to GR might imply the unexpected trend of H 0 (z).…”

“…We do not mention so far which scalar field potential we should have in the Jordan frame, mimicking a cosmological constant in a slow-roll and at the same time providing an effective Hubble constant. Considering the cosmological dynamics in the Jordan frame, we can infer V (φ) [10], if we assume the behavior of H 0 (z) in Eq. ( 10) and the ansatz above for φ (z) in Eq.…”

“…We decide to follow a binned approach using the Pantheon sample dataset to evaluate if the Hubble constant evolves with the redshift [9,10], motivated by the fact the independent measurements of H 0 referred to different redshifts had shown a tension. Therefore, we have split the redshift range of the Pantheon sample in bins each having the same number N of SNe Ia.…”

“…Since the H 0 tension concerns measurements referred to the early and late Universe, in this work we investigate the possibility of a hidden evolutionary effect that could imply a running Hubble constant with the redshift [7,8,9,10], focusing on the data analysis of the Pantheon sample [11]. In this regard, we follow a binned analysis of the Pantheon sample in three and four redshift bins to extract the values of H 0 in each bin.…”