摘要
Recently, a new dark energy model called AHDE was proposed. In this model, dark energy consists of two parts： cosmological constant A and holographic dark energy （HDE）. Two key parameters of this model are the fractional density of cosmological constant Ω2A0, and the dimensionless HDE parameter c. Since these two parameters determine the dynamical properties of DE and the destiny of universe, it is important to study the impacts of different values of ΩA0 and c on the AHDE model. In this paper, we apply various DE diagnostic tools to diagnose AHDE models with different values of ΩA0 and c; these tools include statefinder hierarchy {S3^（1） ,S4（1）fractional growth parameter E, and composite null diagnostic （CND）, which is a combination of{S3（1）,S4（1）} and E. We find that： （1） adopting different values of ΩA0 only has quantitative impacts on the evolution of the AHDE model, while adopting different c has qualitative impacts; （2） compared with S（1）, S（41） can give larger differences among the cosmic evolutions of the AHDE model associated with different ΩA0 or different c; （3） compared with the case of using a single diagnostic, adopting a CND pair has much stronger ability to diagnose the AHDE model.
Recently, a new dark energy model called ΛHDE was proposed. In this model, dark energy consists of two parts: cosmological constant Λ and holographic dark energy(HDE). Two key parameters of this model are the fractional density of cosmological constant ?_(Λ0), and the dimensionless HDE parameter c. Since these two parameters determine the dynamical properties of DE and the destiny of universe, it is important to study the impacts of different values of ?_(Λ0) and c on the ΛHDE model. In this paper,we apply various DE diagnostic tools to diagnose ΛHDE models with different values of ?_(Λ0) and c; these tools include statefinder hierarchy{S_3^(1), S_4^(1)}, fractional growth parameter ?, and composite null diagnostic(CND), which is a combination of{S_3^(1), S_4^(1)}and ?. We find that:(1) adopting different values of ?_(Λ0) only has quantitative impacts on the evolution of the ΛHDE model, while adopting different c has qualitative impacts;(2) compared with S_3^(1), S_4^(1) can give larger differences among the cosmic evolutions of the ΛHDE model associated with different ?_(Λ0) or different c;(3) compared with the case of using a single diagnostic, adopting a CND pair has much stronger ability to diagnose the ΛHDE model.
基金
supported by the National Natural Science Foundation of China(Grant No.11405024)
