Could Dark Matter Interactions be an Alternative to Dark Energy ?

TL;DR

This paper explores whether interactions within dark matter could explain the universe's accelerated expansion, offering an alternative to dark energy by analyzing the global dynamics under the IDM scenario.

Contribution

It derives analytical solutions for the universe's density evolution in the IDM framework, showing it can mimic dark energy effects through disequilibrium in DM particle processes.

Findings

IDM can produce accelerated expansion similar to dark energy models

The effective annihilation term is small, consistent with recent experiments

Analytical solutions match observational Hubble data

Abstract

We study the global dynamics of the universe within the framework of the Interacting Dark Matter (IDM) scenario. Assuming that the dark matter obeys the collisional Boltzmann equation, we can derive analytical solutions of the global density evolution, which can accommodate an accelerated expansion, equivalent to either the {\em quintessence} or the standard $\Lambda$ models, with the present time located after the inflection point. This is possible if there is a disequilibrium between the DM particle creation and annihilation processes with the former process dominating, which creates an effective source term with negative pressure. Comparing the predicted Hubble expansion of one of the IDM models (the simplest) with observational data we find that the effective annihilation term is quite small, as suggested by a variety of other recent experiments.