Dynamical behavior in mimetic F(R) gravity

TL;DR

This paper analyzes the cosmological dynamics of mimetic F(R) gravity, revealing that while it influences early and intermediate universe evolution, late-time behavior aligns with standard F(R) gravity, though perturbations may differ.

Contribution

It provides a detailed dynamical analysis of mimetic F(R) gravity for various F(R) forms, highlighting differences in perturbations despite similar late-time background evolution.

Findings

Late-time universe states match those of usual F(R) gravity.

Mimetic F(R) affects early and intermediate evolution.

Perturbation behavior differs due to new terms.

Abstract

We investigate the cosmological behavior of mimetic F(R) gravity. This scenario is the F(R) extension of usual mimetic gravity classes, which are based on re-parametrizations of the metric using new, but not propagating, degrees of freedom, that can lead to a wider family of solutions. Performing a detailed dynamical analysis for exponential, power-law, and arbitrary F(R) forms, we extracted the corresponding critical points. Interestingly enough, we found that although the new features of mimetic F(R) gravity can affect the universe evolution at early and intermediate times, at late times they will not have any effect, and the universe will result at stable states that coincide with those of usual F(R) gravity. However, this feature holds for the late-time background evolution only. On the contrary, the behavior of the perturbations is expected to be different since the new term contributes to the perturbations even if it does not contribute at the background level.