Thermodynamical description of the ghost dark energy model

Abstract

In this paper, we point out thermodynamical description of ghost dark energy and its generalization to the early universe. Thereinafter, we find expressions for the entropy changes of these dark energy candidates. In addition, considering thermal fluctuations, thermodynamics of the dark energy component interacting with a dark matter sector is addressed. {We will also find the effects of considering the coincidence problem on the mutual interaction between the dark sectors, and thus the equation of state parameter of dark energy.} Finally, we derive a relation between the mutual interaction of the dark components of the universe, accelerated with the either ghost dark energy or its generalization, and the thermodynamic fluctuations.Comment: 11 page

Thermodynamical Description of Modified Generalized Chaplygin Gas Model of Dark Energy

“…In deriving the last equation, we used (21) and (25). Equation (34) gives us an expression for the higher order terms of the thermal fluctuations (S 2 D ) which was omitted in the previous works [90,98,[100][101][102][103]. Moreover, we should note that since the S 0 D and S 1 D terms have the major contributions in the expression (36), one can withdraw the S 2 D contribution, and writes [90,98,[100][101][102][103] …”

“…These corrections are not limited to the gravitational system and indeed, they are available in all thermodynamical systems [100]. In the cosmological setups, thermal fluctuations of system may be attributed to the mutual interaction between the dark sectors [90,98,[101][102][103]. It should be noted that in these attempts the thermal fluctuations up to the first order are investigated.…”

“…It should be noted that in these attempts the thermal fluctuations up to the first order are investigated. It is also shown that the coincidence problem leads to a constraint on the coupling constant of mutual interaction between the ghost dark energy or its generalization form, as the DE candidates, and the pressureless DM [103]. Therefore, it is useful to study the thermodynamics of mutual interaction between the dark sectors of cosmos helping us to get a more actual model for describing DE.…”

“…Finally, we point to the results of considering the coincidence problem on the mutual interaction between the dark sectors. Unlike the previous attempts [90,98,[101][102][103], we do not confine ourselves to the zeroth and first orders thermal fluctuations. The paper is organized as follows.…”

Ghost Dark Energy Model with Non-linear Interaction

“…This vacuun energy density in the QCD ghost dark energy model is proportional to the Hubble parameter H and the proportional coefficient is of the order Λ 3 QCD , where Λ QCD is the mass scale of QCD. From this proposal, many studies in different contexts have been carried out in recent years [14,15,16,17,18,19,20,21,22,23]. The generalization of the ghost dark energy model was carried out in [24], where the studied energy density is of the form ρ Λ = αH + βH 2 .…”