  We study flat space cosmologies in two dimensions by taking the flat space
limit of the Achucarro-Ortiz model. We unravel a phase transition between hot
flat space and flat space cosmologies, and derive a new dilaton-dependent
counterterm required for the consistency of the Euclidean partition function.
Our results generalize to asymptotically mass-dominated 2-dimensional dilaton
gravity models, whose thermodynamical properties we discuss. The novel case of
asymptotic mass-domination is neither covered by the comprehensive discussion
of hep-th/0703230 nor by the more recent generalization to dilaton gravity with
confining U(1) charges in 1406.7007.
