The effect of anisotropy on the thermodynamics of the interacting holographic dark energy model

Abstract

By considering a holographic model for the dark energy in an anisotropic universe, the thermodynamics of a scheme of dark matter and dark energy interaction has been investigated. The results suggest that when holographic dark energy and dark matter evolve separately, each of them remains in thermodynamic equilibrium, therefore the interaction between them may be viewed as a stable thermal fluctuation that brings a logarithmic correction to the equilibrium entropy. Also the relation between the interaction term of the dark components and this thermal fluctuation has been obtained. Additionally, for a cosmological interaction as a free function, the anisotropy effects on the generalized second law of thermodynamics have been studied. By using the latest observational data on the holographic dark energy models as the unification of dark matter and dark energy, the observational constraints have been probed. To do this, we focus on observational determinations of the Hubble expansion rate H(z). Finally, we evaluate the anisotropy effects (although low) on various topics, such as the evolution of the statefinder diagnostic, the distance modulus and the spherical collapse from the holographic dark energy model and compare them with the results of the holographic dark energy of the Friedmann-Robertson-Walker and $\Lambda$ CDM models.