Cosmological Thermodynamics in FLRW Model
This chapter is concerned with a thermodynamic analysis on a flat FLRW universe admitting both apparent and event horizons. As the physical system within the cosmological apparent horizon forms a Bekenstein system, so we have considered the Bekenstein entropy and the Hawking temperature on the apparent horizon. However, since the system bounded by the event horizon may not be a Bekenstein system, we have assumed the Clausius relation on the event horizon to determine its entropy variation. Moreover, we have assumed the modified Hawking temperature on the event horizon. Three types of dark energy cosmic fluids have been considered—a perfect fluid with a constant equation of state, an interacting holographic dark energy, and a Chaplygin gas.