Viaggiu entropy and the generalized second law in a flat FLRW Universe

Abstract

Our aim, in this paper, is to study the generalized second law by considering the dynamical apparent horizon to be endowed with the Hawking temperature and the Viaggiu entropy introduced in a pioneering work in 2014. We have devoted our attention to a flat FLRW universe filled with a perfect fluid having a constant equation of state $p=w\rho$. It is worthwhile to note that we have considered both forms of the Hawking temperature, the original one as well as the truncated version. The latter one is generally used during calculations, however, several arguments have been put forward against it. Our analysis yields a startling result. The Viaggiu entropy naturally forbids the phantom era. In other words, the Viaggiu entropy will never allow the EoS parameter to go beyond the Cosmological Constant. This result is in strong agreement with recent observations and we have deduced it purely by thermodynamic means. This is in striking contrast with the results obtained with the Bekenstein-Hawking formalism.

7 pages; v2: Typos corrected, Matches published version

References in corpus (5)

• Friedmann Equations of FRW Universe in Scalar-tensor Gravity, f(R) Gravity and First Law of Thermodynamics
• Thermodynamic route to Field equations in Lanczos-Lovelock Gravity
• Friedmann Equations and Thermodynamics of Apparent Horizons
• Considerations on the thermal equilibrium between matter and the cosmic horizon
• Bekenstein-Hawking entropy in expanding universes from black hole theorems

Cited by in corpus (5)

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• Einstein, Planck and Vera Rubin: relevant encounters between the Cosmological and the Quantum Worlds
• An extended analysis for a generalized Chaplygin gas model
• The Logotropic Dark Fluid: Observational and Thermodynamic Constraints
• The peculiar case of the Viaggiu holographic dark energy