http://arxiv.org/abs/1812.06854

We consider a class of interacting dark energy models in a spatially flat and nonflat FLRW universe where the interaction is characterized by the modified evolution of the pressureless dark matter sector as $a^{-3+\delta (a)}$, in which $a$ is scale factor of the FLRW universe and $\delta (a)$ is related to the interaction function. By assuming the most natural and nonsingular parametrization for $\delta (a)$ as $\delta \left( a\right) =\delta_{0}+\delta _{1}\left( 1-a\right) +\delta _{2}\left( 1-a\right) ^{2}+…$, where $\delta _{i}$’s ($i=0,1,2,3,..$) are constants, we reconstruct the expansion history of the universe for three particular choices of the dark energy sector; namely, the vacuum energy, dark energy with constant equation of state parameter, and dark energy having dynamical equation of state parameter using the observational data from cosmic microwave background radiation, supernovae Type Ia, baryon acoustic oscillations distance measurements and the Hubble parameter measurements at different redshifts. Our analyses show that although the observational data seem to allow a very mild interaction in the dark sector but within 68\% CL, the non-interacting scenario is recovered. Our reconstruction technique shows that the parameters $\delta _{2}$ and $\delta _{3}$ are almost zero for any interaction model and thus the effective scenario is well described by the linear parametrization $\delta(a) \simeq \delta _{0}+\delta _{1}(1-a)$. We further observe that a strong negative correlation between $\delta_0$ and $\delta_1$ exists independent of different types of dark energy fluid and this is independent of the curvature of our universe. Finally, we remark that for the dark energy sector with constant and dynamical equation of state, the current value of the dark energy equation of state has a tendency towards the phantom regime.

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W. Yang, N. Banerjee, A. Paliathanasis, et. al.
Tue, 18 Dec 18
77/91

Comments: 27 pages, Many Tables and Figures; Comments are welcome