Ernst potentials for vacuum Bianchi models

1993 ◽  
Vol 25 (6) ◽  
pp. 567-578 ◽  
Author(s):  
Nora Bretón
Keyword(s):  
Bianchi Models ◽  
Ernst Potentials

scholarly journals Matrix Ernst potentials for Einstein-Maxwell-dilaton-axion with multiple vector fields

1997 ◽  
Vol 399 (3-4) ◽  
pp. 250-257 ◽  
Author(s):  
D.V. Gal'tsov ◽  
S.A. Sharakin
Keyword(s):  
Vector Fields ◽  
Ernst Potentials

The nonlinear patterns of the cosmic anisotropy: the spatially flat perfect fluid universes.

2021 ◽  
Author(s):  
Leandro Gustavo Gomes
Keyword(s):  
Perfect Fluid ◽  
Hubble Parameter ◽  
Late Time ◽  
Algebraic Equations ◽  
Anisotropic Model ◽  
Bianchi Models ◽  
Principal Directions

Abstract In this manuscript, we investigate the patterns of the cosmological anisotropy in the spatially flat Bianchi models filled with a perfect fluid. We analyse the factor 1 + ∆R, the ratio of the Hubble parameter in the anisotropic model over its isotropic counterpart. In general, ∆R starts to deviate significantly from zero at a specific redshift zA, which depends on the type of the fluid and the value of the anisotropy magnitude. We also show that the deceleration and the jerk along the principal directions of the expansion tensor are constrained by simple algebraic equations that do not depend on the type of matter present. These characteristic patterns form a valuable framework to probe the cosmological anisotropy in the late-time universe.

scholarly journals Oscillatory Singularities in Bianchi Models with Magnetic Fields

2012 ◽  
Vol 14 (5) ◽  
pp. 1043-1075 ◽  
Author(s):  
Stefan Liebscher ◽  
Alan D. Rendall ◽  
Sophonie Blaise Tchapnda
Keyword(s):  
Magnetic Fields ◽  
Bianchi Models

Supersymmetric Bianchi models and the square root of the Wheeler-DeWitt equation

1993 ◽  
Vol 300 (1-2) ◽  
pp. 44-48 ◽  
Author(s):  
P.D. D'Eath ◽  
S.W. Hawking ◽  
O. Obregón
Keyword(s):  
Square Root ◽  
Bianchi Models

scholarly journals Nonlinear Spinor Field in Non-Diagonal Bianchi Type Space-Time

2018 ◽  
Vol 173 ◽  
pp. 02018
Author(s):  
Bijan Saha
Keyword(s):  
Spinor Field ◽  
Bianchi Type ◽  
Space Time ◽  
Coupling Constant ◽  
Nonlinear Spinor ◽  
Bianchi Models ◽  
Rotationally Symmetric ◽  
Big Crunch ◽  
The Universe

Within the scope of the non-diagonal Bianchi cosmological models we have studied the role of the spinor field in the evolution of the Universe. In the non-diagonal Bianchi models the spinor field distribution along the main axis is anisotropic and does not vanish in the absence of the spinor field nonlinearity. Hence within these models perfect fluid, dark energy etc. cannot be simulated by the spinor field nonlinearity. The equation for volume scale V in the case of non-diagonal Bianchi models contains a term with first derivative of V explicitly and does not allow exact solution by quadratures. Like the diagonal models the non-diagonal Bianchi space-time becomes locally rotationally symmetric even in the presence of a spinor field. It was found that depending on the sign of the coupling constant the model allows either an open Universe that rapidly grows up or a close Universe that ends in a Big Crunch singularity.

General class of anisotropic cosmological models with dilaton and magnetic fields

2014 ◽  
Vol 92 (4) ◽  
pp. 289-294 ◽  
Author(s):  
R. Chaubey
Keyword(s):  
Magnetic Fields ◽  
Cosmological Model ◽  
Exact Solutions ◽  
General Class ◽  
Cosmological Parameters ◽  
Dilaton Field ◽  
Field Equations ◽  
Bianchi Models ◽  
General Solutions ◽  
Friedmann Robertson Walker

The Einstein–Maxwell dilaton field equations are considered for four-dimensional anisotropic Bianchi models. The general solutions have been obtained and their properties have been discussed. The exact solutions to the corresponding field equations are obtained for two different physical viable cosmologies. The cosmological parameters have been discussed in detail and it is also shown that the solutions tend asymptotically to isotropic Friedmann–Robertson–Walker cosmological model.

Cosmic No-Hair Theorem for Bianchi Models in Brane-World Scenarios

2003 ◽  
Vol 35 (1) ◽  
pp. 17-23
Author(s):  
Archan Kumar De ◽  
S. Bhanja ◽  
Subenoy Chakraborty
Keyword(s):  
Brane World ◽  
Bianchi Models

The Bianchi models: Then and now

2006 ◽  
Vol 38 (6) ◽  
pp. 1003-1015 ◽  
Author(s):  
G. F. R. Ellis
Keyword(s):  
Bianchi Models
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