科研之友
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摘要
The physical behavior of cosmological solutions to Einstein's field equations for a spatially homogeneous and anisotropic Bianchi type-I space-time have been investigated by taking into account the affect of time varying cosmological parameters viz., gravitational constant (G), cosmological constant (Lambda) and deceleration parameter (q) in scalar-tensor theory of gravitation proposed by Saez and Ballester (Phys. Lett. A 113:467, 1986). The concept of time dependent deceleration parameter with some proper assumption yields the average scale factor a(t) = (sinh(alpha t))(1/n), with n and alpha being positive constants. For 0 < n <= 1, this generates a class of accelerating models while for n > 1, universe models exhibit phase transition from early decelerating phase to present accelerating phase which is corroborated with the results from recent astronomical and astrophysical observations. Moreover, the variability of G has been assumed via the relation 8 pi G proportional to a(m) (m being positive constant) while the time varying behavior of Lambda has been derived. It is observed that Lambda is a positive decreasing function of time, which is in good agreement with the results from recent Supernovae Type Ia observations. Some physical and geometric properties of the model along with physical acceptability of cosmological solutions have been discussed in detail.
- 出版日期2014
