Qualitative dynamics of interacting vacuum cosmologies

Abstract

We present a phase-space analysis of the qualitative dynamics cosmologies where dark matter exchanges energy with the vacuum component. We find fixed points corresponding to power-law solutions where the different components remain a constant fraction of the total energy density and given an existence condition for any fixed points with nonvanishing energy transfer. For some interaction models we find novel fixed points in the presence of a third noninteracting fluid with constant equation of state, such as radiation, where the interacting vacuum+matter tracks the evolution of the third fluid, analogous to tracker solutions previously found for self-interacting scalar fields. We illustrate the phase-plane behavior, determining the equation of state and stability of the fixed points in the case of a simple linear interaction model, for interacting vacuum and dark matter, including the presence of noninteracting radiation. We give approximate solutions for the equation of state in matter- or vacuum-dominated solutions in the case of small interaction parameters.

arXiv comment20 pages, 8 figures; corrected a label in Fig. 5(c); typos corrected; references added; updated author's affiliations; matches the published version

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Cited by in corpus (4)

• Interacting dark sector from the trace-free Einstein equations: cosmological perturbations with no instability
• Nonsingular Cosmology from an Interacting Vacuum
• Observational constraints on interacting vacuum energy with linear interactions
• Some Classes of Interacting Two-Fluid Model of the Expanding Universe