Could Dark Matter Interactions be an Alternative to Dark Energy ?

Understand

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.