Scale Factor in non-zero Λ Cosmology, function of k, Ωo
•Behavior can be rather complicated, and…
These are models for which the cosmological constant is, well, a constant.  We don’t know what makes up the accelerative force for sure, if the dark energy density will stay constant (e.g., if it arises from vaccuum fluctuations) or if it evolves strongly with time.  The behavior can be very different (“big rip”).