Thermodynamics of flat FLRW universe in Rastall theory

Abstract

In this paper, after referring to the Rastall theory, we address some of its\ncosmological consequences. Moreover, bearing the Clausius relation in mind,\nusing Friedman equations in Rastall theory and the Cai-Kim temperature, we\nobtain a relation for the apparent horizon entropy of a flat FLRW universe. In\naddition, we impose the entropy positivity condition on the obtained relation\nfor the horizon entropy, to find some constraints on the Rastall parameters.\nMoreover, we investigate the second and generalized second laws of\nthermodynamics. The results of considering a dominated prefect fluid with\nconstant state parameter are also addressed helping us familiarize with the\nRastall theory.\n