Cosmological Solutions of Tensor–Vector Theories of Gravity by Varying the Space-Time–Matter Coupling Constant

• Published in: Journal of astrophysics and astronomy Vol. 34; no. 1; pp. 41 - 60
• Main Authors: Izadi, A., Shojai, A., Nouradini, M.
• Format: Journal Article
• Language: English
• Published: India Springer-Verlag 01.03.2013; Springer Nature B.V
• Subjects: Astronomy; Astrophysics; Astrophysics and Astroparticles; Dynamical systems; Gravity; Observations and Techniques; Physics; Physics and Astronomy; Universe; Speed of light—tensor–vector theories—dynamical system method—horizon problem
• ISSN: 0250-6335; 0973-7758
• DOI: 10.1007/s12036-013-9162-z

We consider tensor–vector theories by varying the space-time–matter coupling constant (varying Einstein velocity) in a spatially flat FRW universe. We examine the dynamics of this model by dynamical system method assuming a ΛCDM background and we find some exact solutions by considering the character of critical points of the theory and their stability conditions. Then we reconstruct the potential V ( A 2 ) and the coupling Z ( A 2 ) by demanding a background ΛCDM cosmology. Also we set restrictions on the varying Einstein velocity to solve the horizon problem. This gives a selection rule for choosing the appropriate stable solution. We will see that it is possible to produce the background expansion history H ( z ) indicated by observations. Finally we will discuss the behavior of the speed of light ( c E ) for those solutions.