Dynamics of Quintessence with Thermal Interactions

The cosmological dynamics of minimally coupled scalar field that couple to the background matter with thermal interactions is investigated in exponential potential. The conditions for the existence and stability of various critical points as well as their cosmological implications are obtained. Although we show that the effects of thermal interaction such as depressing the equation-of-state parameter of quintessence, is only important at the early time, the evolution of equation-of-state parameter of quintessence is manifested. The upper bound is required on the coupling between quintessence and relativistic relic particles such as photons and neutrinos.