Testing gravity theories using cosmological observations

Abstract

Recent cosmological observations show that there is a growing tension in the expansion rate of the Universe and that the standard cosmological model ΛCDM, based on Einstein’s theory of General relativity (GR), is not sufficient enough to explain or relieve this tension. This tension was first noted by the Planck Collaboration amidst other contributors. A possibility that may alleviate this tension considers extensions or alternative theories of gravity. This works considers an alternative theory of gravity identified as Teleparallel Gravity (TG). In a certain limit, TG can produce a Teleparallel Equivalent of General Relativity (TEGR). In particular, this work reconstructs the equations for the extensions of TEGR known as f(T) and f(T,B) in a model-independent way using Gaussian Processes and observational datasets only. This novel data analyses technique is then used to constrain these modified theories of gravity against observational data.