Entropic cosmology in a dissipative universe

• Komatsu, Nobuyoshi

• Kimura, Shigeo

抄録

The bulk viscosity of cosmological fluid and the creation of cold dark matter both result in the generation of irreversible entropy (related to dissipative processes) in a homogeneous and isotropic universe. To consider such effects, the general cosmological equations are reformulated, focusing on a spatially flat matter-dominated universe. A phenomenological entropic-force model is examined that includes constant terms as a function of the dissipation rate ranging from μ=0, corresponding to a nondissipative ΛCDM (lambda cold dark matter) model, to μ=1, corresponding to a fully dissipative CCDM (creation of cold dark matter) model. A time-evolution equation is derived for the matter density contrast in order to characterize density perturbations in the present entropic-force model. It is found that the dissipation rate affects the density perturbations even if the background evolution of the late universe is equivalent to that of a fine-tuned pure ΛCDM model. With increasing dissipation rate μ, the calculated growth rate for the clustering gradually deviates from observations, especially at low redshifts. However, the growth rate for low μ(less than 0.1) is found to agree well with measurements. A low-dissipation model predicts a smaller growth rate than does the pure ΛCDM model (for which μ=0). More detailed data are needed to distinguish the low-dissipation model from the pure ΛCDM one.

収録刊行物

• Physical Review D - Particles, Fields, Gravitation and Cosmology

  Physical Review D - Particles, Fields, Gravitation and Cosmology 90 (12), 123516-, 2014-12-12

  American Physical Society

詳細情報

• CRID: 1050564285890153856
• NII論文ID: 120005537872
• NII書誌ID: AA00773624
• ISSN: 15507998
• Web Site: http://hdl.handle.net/2297/40591
• 本文言語コード: en
• 資料種別: journal article
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