Cosmological Models in Lyra Geometry with Linearly Varying Deceleration Parameter

2018 ◽  
Author(s):  
Kalyani Desikan
Keyword(s):  
Exact Solutions ◽  
Displacement Field ◽  
Deceleration Parameter ◽  
Lyra Geometry ◽  
Cosmological Models ◽  
Time Dependent ◽  
Linearly Varying Deceleration Parameter ◽  
Frw Model ◽  
Time Periods ◽  
The Universe

Cosmological models with linearly varying deceleration parameter in the cosmological theory based on Lyra’s geometry have been discussed. Exact solutions have been obtained for a spatially flat FRW model by considering a time dependent displacement field. We have also obtained the time periods during which the universe undergoes decelerated and accelerated expansions for a matter-dominated universe.

scholarly journals THE STRING COUPLING ACCELERATES THE EXPANSION OF THE UNIVERSE

2005 ◽  
Vol 14 (12) ◽  
pp. 2327-2333
Author(s):  
JOHN ELLIS ◽  
NIKOLAOS E. MAVROMATOS ◽  
DIMITRI V. NANOPOULOS
Keyword(s):  
String Theory ◽  
Deceleration Parameter ◽  
Cosmological Models ◽  
Rate Of Change ◽  
Negative Sign ◽  
Time Dependent ◽  
Expansion Of The Universe ◽  
Present Rate ◽  
The Universe

Generic cosmological models in non-critical string theory have a time-dependent dilaton background at a late epoch. The cosmological deceleration parameter q0 is given by the square of the string coupling, [Formula: see text], up to a negative sign. Hence, the expansion of the universe must accelerate eventually, and the observed value of q0 corresponds to [Formula: see text]. In this scenario, the string coupling is asymptotically free at large times, but its present rate of change is imperceptibly small.

scholarly journals LRS BIANCHI TYPE-I COSMOLOGICAL MODELS IN BARBER'S SECOND SELF CREATION THEORY

2002 ◽  
Vol 11 (08) ◽  
pp. 1195-1207 ◽  
Author(s):  
ANIRUDH PRADHAN ◽  
ANIL KUMAR VISHWAKARMA
Keyword(s):  
Physical Properties ◽  
Exact Solutions ◽  
Perfect Fluid ◽  
Deceleration Parameter ◽  
Bianchi Type ◽  
Cosmological Models ◽  
Type I ◽  
Fluid Source ◽  
Bianchi Type I ◽  
Radiation Universe

Barber's second self creation theory with perfect fluid source for an LRS Bianchi type-I metric is considered using deceleration parameter to be constant where the metric potentials are taken as functions of x and t. In particular, some exact solutions have also been obtained for the vacuum universe, Zel'dovich universe and radiation universe. Some physical properties of the models are also discussed.

scholarly journals LITTLE RIP COSMOLOGICAL MODELS WITH TIME-DEPENDENT EQUATION OF STATE

2012 ◽  
Vol 27 (36) ◽  
pp. 1250210 ◽  
Author(s):  
I. BREVIK ◽  
V. V. OBUKHOV ◽  
K. E. OSETRIN ◽  
A. V. TIMOSHKIN
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Cosmological Models ◽  
Time Dependent ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Energy Models ◽  
Sitter Spacetime ◽  
The Universe ◽  
Far Future

Specific dark energy models, leading to the Little Rip (LR) cosmology in the far future, are investigated. Conditions for the occurrence of LR in terms of the parameters present in the proposed equation of state for the dark energy cosmic fluid are studied. Estimates about the time needed before the occurrence of the small singularity in the standard LR model in which the universe approaches the de Sitter spacetime asymptotically, are given.

scholarly journals Anisotropic magnetized holographic Ricci dark energy cosmological models

2017 ◽  
Vol 95 (4) ◽  
pp. 381-392 ◽  
Author(s):  
M. Vijaya Santhi ◽  
V.U.M. Rao ◽  
Y. Aditya
Keyword(s):  
General Relativity ◽  
Dark Energy ◽  
Deceleration Parameter ◽  
Bianchi Type ◽  
Cosmological Models ◽  
Field Equations ◽  
Ricci Dark Energy ◽  
Theor Phys ◽  
Linearly Varying Deceleration Parameter ◽  
Spatially Homogeneous

In this paper, we have considered spatially homogeneous and anisotropic Bianchi type-III space–time filled with matter and anisotropic modified holographic Ricci dark energy in general relativity. We have solved Einstein’s field equations using the following possibilities: (i) hybrid expansion law proposed by Akarsu et al. (JCAP, 01, 022 (2014)); (ii) a varying deceleration parameter considered by Mishra et al. (Int. J. Theor. Phys. 52, 2546 (2013)); and (iii) a linearly varying deceleration parameter given by Akarsu and Dereli (Int. J. Theor. Phys. 51, 612 (2012)). We have presented the cosmological models in each of the preceding cases and studied their evolutions. We have also discussed physical and kinematical properties of the models.

scholarly journals COSMOLOGICAL MODELS WITH A VARYING Λ-TERM IN LYRA'S GEOMETRY

2012 ◽  
Vol 27 (29) ◽  
pp. 1250164 ◽  
Author(s):  
V. K. SHCHIGOLEV
Keyword(s):  
Vector Field ◽  
Exact Solutions ◽  
Equations Of State ◽  
Displacement Vector ◽  
Cosmological Models ◽  
Displacement Vector Field ◽  
Varying Λ ◽  
Lyra’S Geometry ◽  
Model Equations ◽  
The Universe

Cosmological models in Lyra's geometry are constructed and investigated with the assumption of a minimal interaction of matter with the displacement vector field and the dynamical Λ-term. Exact solutions of the model equations are obtained for the different equations of state of the matter, that fills the universe, and for the certain assumptions on the decaying law for Λ.

Sign in / Sign up

Export Citation Format

Share Document