Accelerating scaling solutions from dark matter particle creation

TL;DR

This paper investigates how dark matter particle creation can lead to accelerating universe models without dark energy, identifying specific interaction conditions that produce such scaling attractors.

Contribution

It provides a unified dynamical analysis of various dark matter interaction models, revealing conditions for accelerating scaling attractors without dark energy.

Findings

Accelerating scaling attractors occur when DM interacts based on its density with energy flowing from DM to the second fluid.

Such attractors are present in global and local DM-based interactions, but absent when interaction depends on the second fluid.

The results clarify how matter creation can mimic dark-energy-like behavior without a dark-energy component.

Abstract

This article opens new window to obtain accelerating scaling attractors without any need of dark energy. We study cosmological dynamics in a two-fluid system where pressureless dark matter (DM) undergoes adiabatic particle creation and exchanges energy with a barotropic fluid. Considering six widely used interaction prescriptions, we formulate the corresponding autonomous systems in a compact phase space and perform a unified dynamical analysis. We find that accelerating scaling attractors, namely late-time states where both fluids coexist with fixed energy fractions, arise only when the interaction is controlled by the DM density and energy flows from DM to the second fluid. Such attractors appear in the global and local DM-based interactions, and in the global mixed case, but are entirely absent when the interaction depends on the second fluid or on local mixed terms, which instead drive the universe to a DM-dominated accelerating phase. These results clarify the unique conditions under which matter creation can mimic dark-energy-like behaviour without introducing a dark-energy component.