Dark Energy Oscillations in Mimetic $F(R)$ Gravity

TL;DR

This paper investigates how mimetic $F(R)$ gravity can suppress dark energy oscillations and better match observational data compared to ordinary $F(R)$ gravity, by tuning the mimetic potential and Lagrange multiplier.

Contribution

It demonstrates that mimetic $F(R)$ gravity can naturally reduce dark energy oscillations without power-law modifications, improving alignment with observations.

Findings

Dark energy oscillations are mitigated in mimetic $F(R)$ gravity.

Present-day dark energy parameters align better with data.

Growth factor evolution is consistent with observational constraints.

Abstract

In this paper we address the problem of dark energy oscillations in the context of mimetic $F(R)$ gravity with potential. The issue of dark energy oscillations can be a problem in some models of ordinary $F(R)$ gravity and a remedy that can make the oscillations milder is to introduce additional modifications in the functional form of the $F(R)$ gravity. As we demonstrate the power-law modifications are not necessary in the mimetic $F(R)$ case, and by appropriately choosing the mimetic potential and the Lagrange multiplier, it is possible to make the oscillations almost to vanish at the end of the matter domination era and during the late-time acceleration era. We examine the behavior of the dark energy equation of state parameter and of the total effective equation of state parameter as functions of the redshift and we compare the resulting picture with the ordinary $F(R)$ gravity case. As we also show, the present day values of the dark energy equation of state parameter and of the total effective equation of state parameter are in better agreement with the observational data, in comparison to the ordinary $F(R)$ gravity case. Finally, we study the evolution of the growth factor as a function of the redshift for all the mimetic models we shall use.