Confronting hubble tension using scalar-tensor theories

Abstract

The Hubble tension, an ongoing debate in astrophysics and cosmology, pertains to different measures of the universe’s current rate of expansion, the Hubble constant (H0). This tension stems from discrepancies in the results acquired using various observational techniques and datasets. To better understand and possibly resolve these differences, it is necessary to investigate different cosmological theories. An interesting path is to modify the basic character of gravity by investigating theories such as scalar-tensor models, which include a scalar field as an extra degree of freedom. These changes seek to correlate theoretical predictions with empirical evidence, perhaps providing fresh insights into the universe’s fundamental features. In this project, cosmological models are analysed using the MCMC technique and the emcee Python toolkit, with an emphasis on the exponential and Higgs scalar field models. The MCMC approach allows for a thorough statistical study of parameter spaces by utilising current Hubble parameter measurements and other observational data, such as CC and Sn Ia. These models are then compared to the ΛCDM model, which provides the benchmark, evaluating their effectiveness in resolving the Hubble tension and establishing tighter restrictions on cosmological parameters. In comparison to the ΛCDM model, the scalar field models displayed a slightly lower value of H0 and hence a slightly larger value of Ωm,0. The inclusion of priors provided larger values of H0 for all models.