Old Dark Energy

Understand

Dark energy dynamics in the recent universe is influenced by its evolution through the long, matter dominated expansion history.

• A particular dynamical property, the flow variable, remains constant in several classes of scalar field models as long as matter dominates; the dark energy is only free to diverge in behavior at recent times.
• This gives natural initial conditions for Monte Carlo studies of dark energy dynamics.
• We propose a parametrization for the later evolution that covers a wide range of possible behaviors, is tractable in making predictions, and can be constrained by observations.