k-essence cosmologies in Kantowski–Sachs and Bianchi space–times

2015 ◽  
Vol 93 (11) ◽  
pp. 1319-1323 ◽  
Author(s):  
T. Singh ◽  
R. Chaubey ◽  
Ashutosh Singh
Keyword(s):  
General Solution ◽  
Scalar Potential ◽  
Kinetic Function ◽  
Locally Rotationally Symmetric ◽  
Bianchi I ◽  
Initial Anisotropy ◽  
Rotationally Symmetric ◽  
Bianchi Iii ◽  
Function Models ◽  
Friedmann Robertson Walker

We investigate Kantowski–Sachs, locally rotationally symmetric Bianchi-I and Bianchi-III cosmology with k-essence and found a set of models that dissipate the initial anisotropy. We obtain the conditions leading to a regular bounce of the average geometry. We show that the linear k-field and polynomial kinetic function models evolve asymptotically to Friedmann–Robertson–Walker cosmologies. For linear k-essence we find the general solution in these cosmologies, when the k-field is driven by an inverse scalar potential.

scholarly journals Averaging generalized scalar field cosmologies II: locally rotationally symmetric Bianchi I and flat Friedmann–Lemaître–Robertson–Walker models

2021 ◽  
Vol 81 (6) ◽  
Author(s):  
Genly Leon ◽  
Sebastián Cuéllar ◽  
Esteban González ◽  
Samuel Lepe ◽  
Claudio Michea ◽  
...  
Keyword(s):  
Scalar Field ◽  
Nonlinear Dynamical Systems ◽  
Perturbation Parameter ◽  
Time Dependent ◽  
Late Time ◽  
De Sitter ◽  
Time Dynamics ◽  
Locally Rotationally Symmetric ◽  
Bianchi I ◽  
Rotationally Symmetric

AbstractScalar field cosmologies with a generalized harmonic potential and a matter fluid with a barotropic equation of state (EoS) with barotropic index $$\gamma $$ γ for the locally rotationally symmetric (LRS) Bianchi I and flat Friedmann–Lemaître–Robertson–Walker (FLRW) metrics are investigated. Methods from the theory of averaging of nonlinear dynamical systems are used to prove that time-dependent systems and their corresponding time-averaged versions have the same late-time dynamics. Therefore, the simplest time-averaged system determines the future asymptotic behavior. Depending on the values of $$\gamma $$ γ , the late-time attractors of physical interests are flat quintessence dominated FLRW universe and Einstein-de Sitter solution. With this approach, the oscillations entering the system through the Klein–Gordon (KG) equation can be controlled and smoothed out as the Hubble parameter H – acting as time-dependent perturbation parameter – tends monotonically to zero. Numerical simulations are presented as evidence of such behavior.

scholarly journals DYNAMICS OF MAGNETIZED BULK VISCOUS STRINGS IN BRANS–DICKE GRAVITY

2012 ◽  
Vol 21 (06) ◽  
pp. 1250055 ◽  
Author(s):  
MUHAMMAD SHARIF ◽  
SAIRA WAHEED
Keyword(s):  
Scalar Field ◽  
Power Law ◽  
Universe Model ◽  
Expanding Universe ◽  
Locally Rotationally Symmetric ◽  
Bianchi I ◽  
Rotationally Symmetric ◽  
Bulk Viscous ◽  
Proportionality Relationship

We explore locally rotationally symmetric Bianchi I universe in Brans–Dicke gravity with self-interacting potential by using charged viscous cosmological string fluid. We use a relationship between the shear and expansion scalars and also take the power law for scalar field as well as self-interacting potential. It is found that the resulting universe model maintains its anisotropic nature at all times due to the proportionality relationship between expansion and shear scalars. The physical implications of this model are discussed by using different parameters and their graphs. We conclude that this model corresponds to an accelerated expanding universe for particular values of the parameters.

scholarly journals Rotating and twisting locally rotationally symmetric spacetimes: A general solution

2017 ◽  
Vol 96 (6) ◽  
Author(s):  
Sayuri Singh ◽  
George F. R. Ellis ◽  
Rituparno Goswami ◽  
Sunil D. Maharaj
Keyword(s):  
General Solution ◽  
Locally Rotationally Symmetric ◽  
Symmetric Spacetimes ◽  
Rotationally Symmetric

scholarly journals Averaging generalized scalar field cosmologies I: locally rotationally symmetric Bianchi III and open Friedmann–Lemaître–Robertson–Walker models

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
Genly Leon ◽  
Esteban González ◽  
Samuel Lepe ◽  
Claudio Michea ◽  
Alfredo D. Millano
Keyword(s):  
Scalar Field ◽  
Nonlinear Dynamical Systems ◽  
Time Dependent ◽  
Late Time ◽  
De Sitter ◽  
Time Dynamics ◽  
Locally Rotationally Symmetric ◽  
Rotationally Symmetric ◽  
Bianchi Iii ◽  
Flrw Universe

AbstractScalar field cosmologies with a generalized harmonic potential and a matter fluid with a barotropic Equation of State (EoS) with barotropic index $$\gamma $$ γ for locally rotationally symmetric (LRS) Bianchi III metric and open Friedmann–Lemaître–Robertson–Walker (FLRW) metric are investigated. Methods from the theory of averaging of nonlinear dynamical systems are used to prove that time-dependent systems and their corresponding time-averaged versions have the same late-time dynamics. Therefore, simple time-averaged systems determine the future asymptotic behavior. Depending on values of barotropic index $$\gamma $$ γ late-time attractors of physical interests for LRS Bianchi III metric are Bianchi III flat spacetime, matter dominated FLRW universe (mimicking de Sitter, quintessence or zero acceleration solutions) and matter-curvature scaling solution. For open FLRW metric late-time attractors are a matter dominated FLRW universe and Milne solution. With this approach, oscillations entering nonlinear system through Klein–Gordon (KG) equation can be controlled and smoothed out as the Hubble factor H – acting as a time-dependent perturbation parameter – tends monotonically to zero. Numerical simulations are presented as evidence of such behaviour.

scholarly journals Quantum Kasner transition in a locally rotationally symmetric Bianchi II universe

2021 ◽  
Vol 104 (2) ◽  
Author(s):  
Ana Alonso-Serrano ◽  
David Brizuela ◽  
Sara F. Uria
Keyword(s):  
Locally Rotationally Symmetric ◽  
Rotationally Symmetric
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