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Alleviating the H0 tension in Rastall gravity

2025/08/26 by Mohebi, R., Golanbari, Kh. Saaidi T., Karami, K.
#FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc)

paper · doi:10.48550/arxiv.2508.20129

Abstract

The tension between measurements of the Hubble constant H0 locally and the value inferred from Planck satellite have provided a strong motivation to explore theoretical frameworks beyond the standard cosmological model (ΛCDM). To this aim, we investigate the H0 tension in the Rastall ΛCDM model (R-ΛCDM), formulated within the Rastall gravity framework as a phenomenological extension of General Relativity featuring a non-conserved energy-momentum tensor. To constrain the cosmological parameters, we employ a comprehensive combined dataset including Big Bang Nucleosynthesis (BBN), Hubble parameter H(z), Type Ia supernovae (SNe Ia), Baryon Acoustic Oscillations (BAO), Cosmic Microwave Background (CMB) anisotropies, and the growth rate of cosmic structures f(z)σ8(z). The estimation of model parameters is performed via Markov Chain Monte Carlo (MCMC) sampling within a Bayesian statistical framework. Our results show that the R-ΛCDM model, especially in closed geometry, reduces the H0 tension, bringing the discrepancy with the local SH0ES measurements down to 1.97σ to 2.18σ. However, the tension related to the σ8 parameter remains unresolved.

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