arXiv subjects

M. C. Calik

Publications and source records attributed to M. C. Calik.

2 recordsLinked to original sources

arXiv2008

Friedmann Equation for Brans Dicke Cosmology

In the context of Brans-Dicke scalar tensor theory of gravitation, the cosmological Friedmann equation which relates the expansion rate $H$ of the universe to the various fractions of energy density is analyzed rigorously. It is shown that Brans-Dicke scalar tensor theory of gravitation brings a negligible correction to the matter density component of Friedmann equation. Besides, in addition to $Ω_Λ$ and $Ω_{M}$ in standard Einstein cosmology, another density parameter, $Ω_{_Δ}$, is expected by the theory. This implies that if $Ω_{_Δ}$ is found to be nonzero, data will favor this model instead of the standard Einstein cosmological model with cosmological constant and will enable more accurate predictions for the rate of change of Newtonian gravitational constant in the future.

gr-qc↗

arXiv2005

Primordial and asymptotic inflation in Brans-Dicke cosmology

The basic motivation of this work is to attempt to explain the rapid primordial inflation and the observed slow late-time inflation by using the Brans-Dicke theory of gravity. We show that the ratio of these two inflation parameters is proportional to the square root of the Brans-Dicke parameter $% ω$ $(ω\gg1) $. We also calculate the Hubble parameter $% H$ and the time variation of the time dependent Newtonian gravitational constant $G$ for both regimes. The variation of the Hubble parameter predicted by Brans-Dicke cosmology is shown to be consistent with recent measurements: The value of $H$ in the late-time future is predicted as 0.86 times the present value of $H$.

gr-qc↗