The varying cosmological constant: a new approximation to the Friedmann equations and universe model

Basit Öğe Kaydı
dc.authoridOztas, Ahmet Mecit/0000-0002-3508-3227
dc.authoridSmith, Michael Lee/0000-0003-4103-8614
dc.authoridDil, Emre/0000-0002-9042-7694
dc.contributor.authorOztas, Ahmet M.
dc.contributor.authorDil, Emre
dc.contributor.authorSmith, Michael L.
dc.date.accessioned2025-03-23T19:34:19Z
dc.date.available2025-03-23T19:34:19Z
dc.date.issued2018
dc.departmentSinop Üniversitesi
dc.description.abstractWe 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.
dc.identifier.doi10.1093/mnras/sty221
dc.identifier.endpage458
dc.identifier.issn0035-8711
dc.identifier.issn1365-2966
dc.identifier.issue1
dc.identifier.scopus2-s2.0-85043499721
dc.identifier.scopusqualityQ1
dc.identifier.startpage451
dc.identifier.urihttps://doi.org/10.1093/mnras/sty221
dc.identifier.urihttps://hdl.handle.net/11486/5652
dc.identifier.volume476
dc.identifier.wosWOS:000429276700036
dc.identifier.wosqualityQ1
dc.indekslendigikaynakWeb of Science
dc.indekslendigikaynakScopus
dc.language.isoen
dc.publisherOxford Univ Press
dc.relation.ispartofMonthly Notices of the Royal Astronomical Society
dc.relation.publicationcategoryMakale - Uluslararası Hakemli Dergi - Kurum Öğretim Elemanı
dc.rightsinfo:eu-repo/semantics/closedAccess
dc.snmzKA_WOS_20250323
dc.subjectequation of state
dc.subjectcosmological parameters
dc.subjectdark energy
dc.subjectdistance scale
dc.subjectcosmology: theory
dc.titleThe varying cosmological constant: a new approximation to the Friedmann equations and universe model
dc.typeArticle

Dosyalar

Koleksiyon

WoS İndeksli Yayınlar Koleksiyonu
Scopus İndeksli Yayınlar Koleksiyonu