Signature flip in deceleration parameter: a thermodynamic phase transition?

Abstract

Abstract Using the Hayward–Kodama temperature for the apparent horizon, it is found that matter content in the Universe is not thermodynamically stable, and the entry to the late accelerated expansion is actually a second order phase transition. The cosmological model used for the purpose is one that imitates the $$\varLambda $$ Λ CDM model, the favoured model for the present Universe.