The varying cosmological constant: a new approximation to the Friedmann equations and universe model
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Tarih
2018
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Oxford Univ Press
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
We investigate the time-dependent nature of the cosmological constant, Lambda, of the Einstein Field Equation (EFE). Beginning with the Einstein-Hilbert action as our fundamental principle we develop a modified version of the EFE allowing the value of Lambda to vary as a function of time, Lambda (t), indirectly, for an expanding universe. We follow the evolving Lambda presuming four-dimensional space-time and a flat universe geometry and present derivations of Lambda (t) as functions of the Hubble constant, matter density, and volume changes which can be traced back to the radiation epoch. The models are more detailed descriptions of the Lambda dependence on cosmological factors than previous, allowing calculations of the important parameters, Omega(m) and Omega(r), to deep lookback times. Since we derive these without the need for extra dimensions or other special conditions our derivations are useful for model evaluation with astronomical data. This should aid resolution of several difficult problems of astronomy such as the best value for the Hubble constant at present and at recombination.
Açıklama
Anahtar Kelimeler
equation of state, cosmological parameters, dark energy, distance scale, cosmology: theory
Kaynak
Monthly Notices of the Royal Astronomical Society
WoS Q Değeri
Q1
Scopus Q Değeri
Q1
Cilt
476
Sayı
1
