Extended teleparallel scalar-tensor theory : reconstructed models and observational constraints

Abstract

The standard model of cosmology, or ΛCDM, is currently reported to be in 5σ tension when comparing constraints on the value of the Hubble constant using data from the cosmic microwave background radiation (from the recent ESA Planck Mission) and late time observations from our local Universe. This has prompted a search for new cosmological models, some of which explore the possibility of new descriptions of gravity. The core focus of these modifications to ΛCDM cosmology is to provide a better description of the evolution of the Universe, and to provide a more fundamental description of dark energy. In this project, the framework of f(T , ϕ ˆ ) gravity — a formalism that employs Teleparallel Gravity at its core — is used to reconstruct cosmological models with the intent of mimicking our recent cosmological history. The models that are developed are then constrained against observational data from cosmic chronometers and supernovae. This provides not only a sound theoretical basis on which to build these models but also clears numerical constraints on the parameters related to the model, including the Hubble constant. In the end, through one of the investigated models, it is seen that f(T , ϕ ˆ ) gravity is a prospective choice for providing a more definite explanation of gravity.