Dark Energy Evolution: Non-Interacting and Interacting Cases

Abstract

In this paper, we study dark energy from two different perspectives, challenging a two-field scenario in two forms: non-interacting and interacting. We investigate the evolution of dark energy in a Friedmann-Robertson-Walker space-time that is spatially homogeneous and isotropic and filled with two components: dark energy and a barotropic fluid. We examine this evolution from two different perspectives: noninteracting and interacting; and we did it by selecting a suitable ansatz for the scale factor that reflects the transition of the universe from the early decelerating phase to the late accelerated stage. We calculate parameters and quantities such as pressure p, energy density ρ, equation of state (EoS), deceleration parameter q, etc., and compare the results of these two cases with the latest observational data as well as other works in the literature. We discuss the stability of these two different scenarios by calculating the sound speed. We also show whether different energy conditions are satisfied or violated. Then, we explore the evolutionary paths and the dynamical analysis of the model with the help of important tools such as the statefinder diagnostic (r, s) and discuss the results in detail. Finally, we reconstruct the scalar field's potential and test some conjectures using the equation of the state of dark energy and the relation between energy density and pressure with the scalar field and potential. Then, we discuss the results in detail. An important issue that we found in this calculation is the dissatisfaction of the swampland conjectures with this model in non-interacting cases but in the face of swampland conjectures, some acceptable range for t < 2 is seen for all universes in interacting cases.