Interacting dark energy: the role of microscopic feedback in the dark sector

TL;DR

This paper explores how a non-minimal coupling between dark matter and dark energy affects their dynamics, revealing that microscopic feedback can significantly influence structure formation and cosmic evolution.

Contribution

It introduces a new constraint on the smoothness of dark energy scalar field variations and demonstrates the impact of microscopic feedback through numerical simulations.

Findings

Standard results hold only if the scalar field variation is smooth.

Violation of the constraint causes microscopic feedback effects.

Feedback influences dark matter dynamics and structure formation.

Abstract

We investigate the impact on the classical dynamics of dark matter particles and dark energy of a non-minimal coupling in the dark sector, assuming that the mass of the dark matter particles is coupled to a dark energy scalar field. We show that standard results can only be recovered if the space-time variation of the dark energy scalar field is sufficiently smooth on the characteristic length scale of the dark matter particles, and we determine the associated constraint dependent on both the mass and radius of the dark matter particles and the coupling to the dark energy scalar field. We further show, using field theory numerical simulations, that a violation of such constraint results in a microscopic feedback effect strongly affecting the dynamics of dark matter particles, with a potential impact on structure formation and on the space-time evolution of the dark energy equation of state.