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In this paper, the strong gravitational lensing is explored for traversable wormholes in f (R , T) theory of gravity with minimally-coupled massless scalar field. First, the effective wormhole solutions are obtained using the model f (R , T) = R + 2 λ T , where λ is constant, R is scalar curvature and T is the trace of stress-energy tensor. Furthermore, three different shape functions namely, b (r) = r 0 exp (r − r 0) (Ref. 36), b (r) = r 0 (log (r + 1)) log (r 0 + 1) (Refs. 35 and 37) and b (r) = r 0 r r 0 γ , 0 < γ < 1 (Refs. 34, 35, 39, 73) are considered and studied their qualitative behavior for the construction of wormhole geometry respectively. Subsequently, gravitational lensing effect is implemented to detect the existence of photon spheres at or outside the throat of wormholes. [ABSTRACT FROM AUTHOR]

In this work we try to understand the late-time acceleration of the universe by assuming some modification in the geometry of the space and using dynamical system analysis. This technique allows to understand the behavior of the universe without analytically solving the field equations. We study the acceleration phase of the universe and stability properties of the critical points which could be compared with observational results. We consider an asymptotic behavior of two particular models f (R) = R − μ R c (R / R c) 2 n (R / R c) 2 n + 1 and f (R) = R − μ R c 1 − 1 + R 2 / R c 2 − n with n , μ , R c > 0 for the study. As a first case we fix the value of μ and analyze for all n. Later as second case, we fix the value of n and calculation are done for all μ. At the end all the calculations for the generalized case have been shown and results have been discussed in detail. [ABSTRACT FROM AUTHOR]

Morris and Thorne1 proposed traversable wormholes, hypothetical connecting tools, using the concept of Einstein's general theory of relativity. In this paper, the modification of general relativity (in particular f (R , T) theory of gravity defined by Harko et al.2) is considered, to study the traversable wormhole solutions. The function f (R , T) is considered as f (R , T) = R + α R 2 + β T , where α and β are controlling parameters. The shape and redshift functions appearing in the metric of wormhole structure have significant contribution in the development of wormhole solutions. We have considered both variable and constant redshift functions with a logarithmic shape function. The energy conditions are examined, geometric configuration is analyzed and the radius of the throat is determined in order to have wormhole solutions in absence of exotic matter. [ABSTRACT FROM AUTHOR]

The late time accelerated expansion of the universe can be realized using scalar fields with the given self-interacting potentials. Here, we consider a straightforward approach where a three cosmic fluid mixture is assumed. The fluids are standard matter perfect fluid, dark matter, and a scalar field with the role of dark energy. A dynamical system analysis is developed in this context. A central role is played by the equation of state which determines the acceleration phase of the models. Determining the domination of a particular fluid at certain stages of the universe history by stability analysis allows, in principle, to establish the succession of the various cosmological eras. [ABSTRACT FROM AUTHOR]