@article{oai:kanazawa-u.repo.nii.ac.jp:00054080,
 author = {小松, 信義 and Komatsu, Nobuyoshi},
 issue = {2},
 journal = {Physical Review D},
 month = {Jan},
 note = {Density perturbations related to structure formations are expected to be different in dissipative and nondissipative universes, even if the background evolution of the two universes is the same. To clarify the difference between the two universes, first-order density perturbations are studied, using two types of holographic cosmological models. The first type is a “Λ(t) model” similar to a time-varying Λ(t) cosmology for the nondissipative universe. The second type is a “BV model” similar to a bulk viscous cosmology for the dissipative universe. To systematically examine the two different universes, a power-law term proportional to Hα is applied to the Λ(t) and BV (bulk-viscous-cosmology-like) models, assuming a flat Friedmann-Robertson-Walker model for the late universe. Here, H is the Hubble parameter and α is a free parameter whose value is a real number. The Λ(t)−Hα and BV−Hα models are used to examine first-order density perturbations for matter, in which the background evolution of the two models is equivalent. In addition, thermodynamic constraints on the two models are discussed, with a focus on the maximization of entropy on the horizon of the universe, extending previous analyses [Phys. Rev. D 100, 123545 (2019); Phys. Rev. D102, 063512 (2020)]. Consequently, the Λ(t)−Hα model for small|α|values is found to be consistent with observations and satisfies the thermodynamic constraints, compared with the BV−Hα model. The results show that the nondissipative universe described by the Λ(t)−Hα model similar to lambda cold dark matter models is likely favored., 金沢大学理工研究域機械工学系},
 title = {Evolution of dissipative and nondissipative universes in holographic cosmological models with a power-law term},
 volume = {103},
 year = {2021}
}