Constraining Interacting Dark Energy Models with Cosmological Data

Abstract

In this dissertation, the background of cosmology has been investigated in the frame￾work of the non-gravitational interaction between dark matter and dark energy mod￾els (IDE), with the latest cosmological data. Although the initial motivation for the IDE models was to alleviate the coincidence problem, recently, the models have be￾come popular to emphasise the discrepancy between the Hubble measurements from the late- and early-cosmological measurements. We take into account the linear phenomenological models namely: Q = ξHρdm (IDE1), Q = ξHρde (IDE2), and Q = 3ξH(ρdm + ρde) (IDE3); and non-linear models such as Q = 3Hξ ρdmρde ρdm+ρde (IDE4) and Q = 3Hξ√ρdmρde (IDE5) to explore the deviation of each model from the ΛCDM model to systematically investigate the implications of alternative cos￾mological scenarios. Using baryonic acoustic oscillation data released from the dark energy spectroscopic instrument (BAO DESI), Pantheon+ Supernovae Type Ia com￾bined with SH0ES Cepheid (PantheonP + SH0ES), and cosmic chronometer (CC ) datasets, we constrain the cosmological parameters Ωm, ξ, ω and H0 for each model. Furthermore, we assess the viability of all models compared to ΛCDM by performing the statistical analysis through Bayesian evidence. The results indicate that one of our models, IDE4, remains a better candidate than the other IDE models. Followed by the IDE5, with potential to reduce the H0 tension, making it the second better viable candidate.