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 螞CDM, based on Einstein鈥檚 theory of General relativity (GR), is not su铿僣ient enough to explain or relieve this tension. This tension was 铿乺st 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 identi铿乪d 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 modi铿乪d theories of gravity against observational data.