Traversable wormhole model with massive gravitons, two fluids, and a variable gravity

Abstract

We construct a new cosmological model based on relativistic theory of gravity characterized by massive gravitons. The new Friedmann–Robertson–Walker model is characterized by the presence of a static traversable wormhole, massive gravitons, and a variable gravitational coupling constant. To recover the Bianchi identity, a second cosmic fluid is introduced in the theory. Motivated from cosmic dark radiation phenomenological arguments, which suggest that the dynamical component of dark energy could be dominated by a bath of dark radiation, we assume that the original cosmic fluid is radiative, whereas the new cosmic fluid is phantom. The total equation of state of our model is equal to −1. The new model is characterized by an effective Hubble parameter. The solutions of the dynamical equations reveal an accelerated universe with a scale factor of hyperbolic type which allows the deceleration parameter to change sign from a decelerating phase to an accelerating phase. We have evaluated the deceleration parameter, the jerk and the present day variations of the gravitational constant which agree with astronomical observations.