Semiclassical treatment of a k-essence effect on cosmic temperature

Resumo

A phenomenological model with quantum fluctuations of matter fields is described for the Cosmic Microwave Background (CMB) radiation evolution in the presence of dark energy in the form of a k-essence scalar field ϕ(t). Our model is realized through a time-dependent oscillator Lagrangian. Here ϕ couples to the scale factor a(t). Themodel gives: (a) the observed variation of a with time and (b) the observed value of the epoch when the universe passed over from decelerated to accelerated phase. These two features have been matched with graphical transcriptions of SNe Ia data. Further, the evolution is sensitive to the presence of an inhomogeneity. Its sensitivity increases as one goes further into the past. The value of the inhomogeneity parameter determines the transition epoch from decelerated to accelerated phase. A positive value of the inhomogeneity parameter leads an earlier transition, and its negative value to a later one. A slightly negative value of the inhomogeneity parameter gives a better agreement with the observed value for the transition time. The formalism also accommodates dark matter in the form of non-relativistic dust without any change in the above scenarios.