Cosmological dynamics of holographic dark energy with non-minimally coupled scalar field
9
Issued Date
2025-07-01
Resource Type
ISSN
00017701
eISSN
15729532
Scopus ID
2-s2.0-105010060884
Journal Title
General Relativity and Gravitation
Volume
57
Issue
7
Rights Holder(s)
SCOPUS
Bibliographic Citation
General Relativity and Gravitation Vol.57 No.7 (2025)
Suggested Citation
Tita A., Gumjudpai B., Srisawad P. Cosmological dynamics of holographic dark energy with non-minimally coupled scalar field. General Relativity and Gravitation Vol.57 No.7 (2025). doi:10.1007/s10714-025-03442-w Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/111245
Title
Cosmological dynamics of holographic dark energy with non-minimally coupled scalar field
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Abstract
In this study, we consider FRW universe filled with matter, non-minimally coupling (NMC) scalar field under V(ϕ)=V0ϕ2 potential and holographic vacuum energy. Dark energy is contributed from both holographic vacuum energy and the NMC scalar field. NMC effective gravitational constant Geff(ϕ), is naturally defined at the action level. Therefore, the gravitational constant in the holographic vacuum density is an effective one, i.e. ρΛ=3c2/8πGeffL2. Apparent horizon is chosen as IR holographic cutoff scale as it is a trapped null surface. There are nine fixed points in this dynamical system with four independent dimensionless parameters. We consider flat case and find that viable cosmological evolution follows the sequence: an initial stiff-fluid-dominated phase, transitioning through a nearly dust-dominated era, and eventually reaching a stable dark energy-dominating state. Stability analysis requires that ξ<0 and 0<c<1 for the theory to be physically valid. Since zero NMC coupling, ξ=0, is not allowed in the autonomous system, the model can not completely recover canonical scalar field case. That is to say, as ξ→0- and c→0+, the model can only approach the canonical scalar case but can not completely recover it. To approach dust or stiff fluid dominations, both magnitudes of the NMC coupling and the holographic parameter must be small. Numerical integration shows that for any allowed values of ξ and c, weff approaches -1 at late times. Increasing of c does not change shape of the weff, but larger c increases weff. As ξ becomes stronger, dust era gradually disappears. Good behaviors of the dynamics require -1≪ξ<0 and 0<c≪1.