Interacting Dark Matter as an Alternative to Dark Energy

TL;DR

This paper explores how interacting dark matter can explain the universe's accelerated expansion without dark energy, by analyzing its dynamics and comparing predictions with observational data.

Contribution

It provides analytical solutions for dark matter density evolution in the IDM framework, showing it can mimic dark energy effects and fit observational data.

Findings

IDM can produce accelerated expansion similar to dark energy.

The effective annihilation term is small, consistent with experimental constraints.

Analytical solutions support IDM as a viable alternative to dark energy.

Abstract

We investigate the global dynamics of the universe within the framework of the Interacting Dark Matter (IDM) scenario. Considering that the dark matter obeys the collisional Boltzmann equation, we can obtain analytical solutions of the global density evolution, which can accommodate an accelerated expansion, equivalent to either the {\em quintessence} or the standard $\Lambda$ models. 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 various experiments.