論文

査読有り 筆頭著者 責任著者
2013年2月26日

Non-adiabatic-like accelerated expansion of the late universe in entropic cosmology

Physical Review D - Particles, Fields, Gravitation and Cosmology
  • Nobuyoshi Komatsu
  • ,
  • Shigeo Kimura

87
4
記述言語
英語
掲載種別
研究論文(学術雑誌)
DOI
10.1103/PhysRevD.87.043531

In "entropic cosmology," instead of a cosmological constant Λ, an extra driving term is added to the Friedmann equation and the acceleration equation, taking into account the entropy and the temperature on the horizon of the universe. By means of the modified Friedmann and acceleration equations, we examine a non-adiabatic-like accelerated expansion of the universe in entropic cosmology. In this study, we consider a homogeneous, isotropic, and spatially flat universe, focusing on the single-fluid- (single-component-) dominated universe at late times. To examine the properties of the late universe, we solve the modified Friedmann and acceleration equations, neglecting high-order corrections for the early universe. We derive the continuity (conservation) equation from the first law of thermodynamics, assuming nonadiabatic expansion caused by the entropy and temperature on the horizon. Using the continuity equation, we formulate the generalized Friedmann and acceleration equations, and propose a simple model. Through the luminosity distance, it is demonstrated that the simple model agrees well with both the observed accelerated expansion of the Universe and a fine-tuned standard ΛCDM (lambda cold dark matter) model. However, we find that the increase of the entropy for the simple model is likely uniform, while the increase of the entropy for the standard ΛCDM model tends to become gradually slower, especially after the present time. In other words, the simple model predicts that the present time is not a special time, unlike for the prediction of the standard ΛCDM model. © 2013 American Physical Society.

リンク情報
DOI
https://doi.org/10.1103/PhysRevD.87.043531
Scopus
https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84874512989&origin=inward
Scopus Citedby
https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84874512989&origin=inward
ID情報
  • DOI : 10.1103/PhysRevD.87.043531
  • ISSN : 1550-7998
  • eISSN : 1550-2368
  • SCOPUS ID : 84874512989

エクスポート
BibTeX RIS