Abstract
We investigate the consequences of non-minimal gravitational coupling to matter and study how it differs from the case of minimal coupling by choosing certain simple forms for the nature of coupling. The values of the parameters are specified at z=0 (present epoch) and the equations are evolved backwards to calculate the evolution of cosmological parameters. We find that the Hubble parameter evolves more slowly in non-minimal coupling case as compared to the minimal coupling case. In both the cases, the universe accelerates around present time, and enters the decelerating regime in the past. Using the latest Union2 dataset for supernova Type Ia observations as well as the data for baryon acoustic oscillation (BAO) from SDSS observations, we constraint the parameters of Linder exponential model in the two different approaches. We find that there is an upper bound on model parameter in minimal coupling. But for non-minimal coupling case, there is range of allowed values for the model parameter.
Highlights
The gravity action becomes, It has become fairly well established that the Universe is undergoing an accelerated expansion in recent times (z ≤ 4)
We find that there is a upper bound on model parameter in minimal coupling
We find that there is an upper bound on model parameter C in the minimal coupling case
Summary
The gravity action becomes, It has become fairly well established that the Universe is undergoing an accelerated expansion in recent times (z ≤ 4). We attempt to place observational constraints on the parameters of this model in both minimal and non-minimal coupling of scalar curvature with matter lagrangian density. We shall consider the cosmological evolutions and their observational constraints for modified gravity models in both cases, namely, one in which the curvature is coupled minimally as well as the one in which the curvature is non-minimally coupled with the matter lagrangian density. The behaviour of q(z) is shown in figure 2 for different values of the model parameter c assuming Ωm = 0.25 and q0 = −0.55 It shows that in all cases, the universe has an accelerated phase at present and as we go back it smoothly enters the decelerating phase. The lower the value of c, the universe enters the accelerated phase earlier
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