Constraints on Rastall gravity from current observational data

Abstract

We study the cosmological features of Rastall gravity, where the covariant energy-momentum conservation is modified to ${\nabla }_{\mu }{T}_{\nu }^{\mu }=\lambda {\nabla }_{\nu }R$ in curved spacetime. For this purpose, we obtain the modified field equations of Rastall model to linear order of perturbations, and then inspect the evolutionary behavior of cosmological observables, chiefly the matter power spectrum and the Hubble parameter, within the context of Rastall gravity. We also compare Rastall model with cosmological probes, namely cosmic microwave background, weak lensing, supernovae, baryon acoustic oscillations, and redshift-space distortions data. According to our numerical results, Rastall gravity prefers lower growth of structures compared to the $\Lambda$CDM model, which indicates consistency with low-redshift large-scale structure probes. Moreover, numerical analysis reveals that Rastall gravity with a cosmological constant as the dark energy component suffers from the Hubble tension, like the $\Lambda$CDM model.

10 pages, 5 figures