Cosmological perturbations in mimetic matter model

TL;DR

This paper explores the cosmological evolution and perturbations of the mimetic matter model with arbitrary scalar potentials, demonstrating its ability to mimic various dark energy and dark matter behaviors and analyzing perturbation dynamics near future singularities.

Contribution

It provides explicit reconstruction of cosmological evolution in mimetic matter models for different potentials and studies the unique behavior of perturbations, especially near singularities.

Findings

Mimetic matter can replicate CDM, wCDM, and dark energy evolutions.

Perturbation behavior differs from standard models, especially near singularities.

Decay of matter density perturbations may occur before future singularities.

Abstract

We investigate the cosmological evolution of mimetic matter model with arbitrary scalar potential. The cosmological reconstruction, which is the way to construct a model for arbitrary evolutions of the scale factor, is explicitly done for different choices of potential. The cases that mimetic matter model shows the evolution as Cold Dark Matter(CDM), wCDM model, dark matter and dark energy with dynamical $Om(z)$, where $Om(z) \equiv [ (H(z)/H_0)^2-1 ]/[(1+z)^3 -1],$ or phantom dark energy with phantom-non-phantom crossing are presented in detail. The cosmological perturbations for such evolution are studied in mimetic matter model. For instance, the evolution behavior of the matter density contrast which is different from usual one, i.e. $\ddot \delta + 2 H \dot \delta - \kappa ^2 \rho \delta /2 = 0$ is investigated. The possibility of peculiar evolution of $\delta$ in the model under consideration is shown. Special attention is paid to the behavior of matter density contrast near to future singularity where decay of perturbations may occur much earlier the singularity.