Journal ArticleDOI
Early homogeneous universe with variable cosmological constant: kinematics tests
Reads0
Chats0
TLDR
In this article, a spatially homogeneous cosmological model with flat geometry filled with perfect fluid is studied in the presence of a variable cosmology "constant." Einstein's field equations are solved by using the "gamma-law" equation of state p = (γ-1)ρ, where the adiabatic parameter γ, varies with cosmic time.Abstract:
A spatially homogeneous cosmological model with flat geometry filled with perfect fluid is studied in the presence of a variable cosmological "constant." Einstein's field equations are solved by using the "gamma-law" equation of state p = (γ-1)ρ, where the adiabatic parameter γ, varies with cosmic time. The functional form of γ, which is assumed to be the function of scale factor R as proposed by Carvalho, is used to describe the early evolution of universe with variable cosmological "constant." A unified description of early universe is given in which an inflationary phase is followed by radiation-dominated phase. It has been observed that the solutions are compatible with the result of recent observations. Exact expressions for the look-back time, proper distance, luminosity distance and angular diameter distance versus redshift are derived and their meaning are discussed in detail. The various physical aspects of the models are also discussed.read more
Citations
More filters
A Relation Between Distance and Radial Velocity Among Extra-Galactic Nebulae
TL;DR: In this article, a re-examination of the relationship between apparent radial velocities and distances is presented, based on only those nebular distances which are believed to be fairly reliable.
Journal ArticleDOI
Kaluza-Klein Type Cosmological Model of Early Universe with Variable Cosmological Term Λ: Kinematic Tests
G. S. Khadekar,Vaishali Kamdi +1 more
TL;DR: In this article, the Kaluza-Klein type cosmological model with variable Λ term in the presence of perfect fluid is considered and exact solution of the field equations by using gamma law equation of state p=(γ−1)ρ, in which parameter γ depends on the scale factor R proposed by Carvalho (Int. J. Theor. Phys. 35:2019, 1996).
Journal ArticleDOI
Inhomogeneous early viscous fluid universe: A concrete model for dark energy
TL;DR: In this paper, the authors investigated the effect of bulk viscosity on the early evolution of the universe and obtained the H-z relation for two different phases of universe and Friedmann equations.
Journal ArticleDOI
Early Universe in Scalar-Tensor Theory
C. P. Singh,Aroonkumar Beesham +1 more
TL;DR: In this paper, the authors considered the flat Robertson-Walker model in scalar-tensor theory and studied how the adiabatic parameter γ should vary so that the universe goes through a transition from an inflationary to a radiation-dominated phase.
Journal ArticleDOI
Bianchi type i cosmological model with varying G, Λ & σ2 in VSL theory
G. S. Khadekar,Arti Ghogre +1 more
TL;DR: In this paper, the Bianchi type I cosmological model in the framework of variable speed of light (VSL) theory was studied and exact expressions for the look back time, proper distance, luminosity distance and angular diameter distance versus redshift were derived.
References
More filters
Journal ArticleDOI
Measurements of Omega and Lambda from 42 High-Redshift Supernovae
Saul Perlmutter,Saul Perlmutter,Greg Aldering,Gerson Goldhaber,Gerson Goldhaber,R. A. Knop,Peter Nugent,P. G. Castro,P. G. Castro,Susana E. Deustua,Sebastien Fabbro,Sebastien Fabbro,A. Goobar,A. Goobar,Donald E. Groom,I. M. Hook,I. M. Hook,A. G. Kim,A. G. Kim,A. G. Kim,M. Y. Kim,Julia C. Lee,Julia C. Lee,Nelson J. Nunes,Nelson J. Nunes,Reynald Pain,Reynald Pain,C. R. Pennypacker,C. R. Pennypacker,Robert Quimby,Christopher Lidman,Richard S. Ellis,Mike Irwin,Richard G. McMahon,Pilar Ruiz-Lapuente,Nicholas A. Walton,Bradley E. Schaefer,B. J. Boyle,Alexei V. Filippenko,Thomas Matheson,A. S. Fruchter,Nino Panagia,Nino Panagia,Heidi Jo Newberg,Warrick J. Couch +44 more
TL;DR: In this paper, the mass density, Omega_M, and cosmological-constant energy density of the universe were measured using the analysis of 42 Type Ia supernovae discovered by the Supernova Cosmology project.
Journal ArticleDOI
Measurements of Omega and Lambda from 42 High-Redshift Supernovae
Saul Perlmutter,Greg Aldering,G. Goldhaber,R. A. Knop,Peter Nugent,P. G. Castro,Susana E. Deustua,Sebastien Fabbro,A. Goobar,D. E. Groom,I. M. Hook,A. G. Kim,M. Y. Kim,Julia C. Lee,Nelson J. Nunes,Reynald Pain,C. R. Pennypacker,R. M. Quimby,C. Lidman,Richard S. Ellis,Michael G. Irwin,Richard G. McMahon,P. Ruiz-Lapuente,Nicholas A. Walton,Bradley E. Schaefer,B. J. Boyle,Alexei V. Filippenko,Thomas Matheson,A. S. Fruchter,Nino Panagia,Heidi Jo Newberg,W. J. Couch +31 more
TL;DR: In this paper, the mass density, Omega_M, and cosmological-constant energy density of the universe were measured by the analysis of 42 Type Ia supernovae discovered by the Supernova Cosmology Project.
Journal ArticleDOI
The Cosmological Constant Problem
TL;DR: In this article, five different approaches to the cosmological constant problem are described, and a brief review of the history of this problem is given. But none of the approaches are considered in this paper.
Journal ArticleDOI
The Cosmological Constant and Dark Energy
P. J. E. Peebles,Bharat Ratra +1 more
TL;DR: A review of dark energy can be found in this paper, where the authors present the basic physics and astronomy of the subject, reviews the history of ideas, assesses the state of the observational evidence, and comments on recent developments in the search for a fundamental theory.
Journal ArticleDOI
Cosmological Consequences of a Rolling Homogeneous Scalar Field
Bharat Ratra,P. J. E. Peebles +1 more
TL;DR: It is argued that a number of models in which the energy density of the scalar field red-shifts in a specific manner are studied could reconcile the low dynamical estimates of the mean mass density with the negligibly small spatial curvature preferred by inflation.