Intrinsic Entropy Perturbations from the Dark Sector

TL;DR

This paper investigates how intrinsic entropy perturbations in the dark sector influence the evolution of curvature perturbations on superhorizon scales, using an effective field theory approach to model dark matter and dark energy as a single perfect fluid.

Contribution

It introduces a self-consistent framework for analyzing intrinsic entropy perturbations in the dark sector and explores their effects on superhorizon curvature dynamics and vorticity behavior.

Findings

Intrinsic entropy perturbations affect superhorizon curvature evolution.

Vorticity dynamics and Weinberg theorem violations are analyzed.

Dark sector modeled as a single perfect fluid with entropy perturbations.

Abstract

Perfect fluids are modeled by using an effective field theory approach which naturally gives a self-consistent and unambiguous description of the intrinsic non-adiabatic contribution to pressure variations. We study the impact of intrinsic entropy perturbation on the superhorizon dynamics of the curvature perturbation ${\cal R}$ in the dark sector. The dark sector, made of dark matter and dark energy is described as a single perfect fluid. The non-perturbative vorticity's dynamics and the Weinberg theorem violation for perfect fluids are also studied.