SSFDE Model: Cosmological Implications and Dynamical System Analysis

TL;DR

This paper investigates an interacting dark energy model with an exponential potential, analyzing its cosmological implications and stability through dynamical systems, and compares it with non-interacting models using recent observational data.

Contribution

It introduces a dynamical systems framework for an interacting scalar field dark energy model and compares its observational viability against non-interacting models.

Findings

Interacting model predicts a lower Hubble constant than CDM with moderate evidence against CDM.

Positive coupling indicates energy transfer from dark matter to dark energy.

Critical points correspond to different cosmic epochs, from stiff matter to late-time acceleration.

Abstract

In this paper, we consider an interacting scalar field dark energy model with an exponential potential and a dark sector coupling \( Q = 3\gamma H\rho_{dm} \), which has been observationally tested using recent baryon acoustic oscillation measurements from the Dark Energy Spectroscopic Instrument Data Release 2 , Unanchored Type Ia Supernovae, and the compressed CMB likelihood. We find that the Interacting model predicts a Hubble constant of $h = 0.659 \pm 0.0063$, deviating from the $\Lambda$CDM value by approximately $2.93\sigma$, while the Non-Interacting model shows a $3.78\sigma$ deviation. The positive coupling parameter (\( \gamma > 0 \)) further suggests a transfer of energy from dark matter to dark energy. According to the Jeffreys scale, the Interacting model shows moderate evidence against the $\Lambda$CDM model, whereas the Non-Interacting model shows only inconclusive evidence. Further, we investigate both models through the lens of dynamical systems analysis. We formulate the cosmological evolution equations with a phenomenological interaction term and recast them into an autonomous system to study the qualitative behavior of cosmic expansion. Critical points of the system are identified and analyzed to study the corresponding cosmological dynamics. In the interacting model, we obtained five critical points, whereas in the non-interacting scenario, four distinct sets of critical points were identified. The obtained critical points, governed by cosmological parameters, represent distinct cosmic epochs, commencing from the early time stiff matter domination to late-time acceleration. Their stability is examined through linear stability analysis under appropriate physical constraints. The evolution of background cosmological parameters are also examined in terms of the dynamical system variable, and the obtained values align with observational results.