Scaling solutions from interacting fluids

TL;DR

This paper explores how interactions between different cosmic fluids influence the universe's evolution, revealing new scaling solutions, oscillatory behaviors, and constraints from nucleosynthesis.

Contribution

It introduces a generalized interaction model between fluids in cosmology, uncovering novel scaling solutions and discussing their implications for inflation and observational constraints.

Findings

Existence of attracting scaling solutions in parameter space

Possibility of oscillating cosmological behaviors

New curvature scaling solutions identified

Abstract

We examine the dynamical implications of an interaction between some of the fluid components of the universe. We consider the combination of three matter components, one of which is a perfect fluid and the other two are interacting. The interaction term generalizes the cases found in scalar field cosmologies with an exponential potential. We find that attracting scaling solutions are obtained in several regions of parameter space, that oscillating behaviour is possible, and that new curvature scaling solutions exist. We also discuss the inflationary behaviour of the solutions and present some of the constraints on the strength of the coupling, namely those arising from nucleosynthesis.