Reconstructing the dark matter and dark energy interaction scenarios from observations

Abstract

We consider a class of interacting dark energy models in a flat and nonflat FLRW universe where the interaction is characterized by the modified evolution of the pressureless dark matter as $a^{-3+\delta (a)}$, $a$ being the FLRW scale factor and $\delta (a)$ quantifies the interaction rate. By assuming the most natural and nonsingular parametrization for $\delta (a)$ as $\delta \left(a\right)={\sum }_i{\delta }_i(1-a{)}^i$, 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 DE sector using different cosmological datasets. Our analyses show that the non-interacting scenario is consistent with the observations while the interaction is not strictly ruled out. We reconstruct in the following way. We start with the first two terms of $\delta (a)$ above and constrain ${\delta }_0$, ${\delta }_1$. Then we consider up to the second order terms in $\delta (a)$ but fix ${\delta }_0$, ${\delta }_1$ to their constrained values and constrain ${\delta }_2$; similarly we constrain ${\delta }_3$, and finally we constrain $({\delta }_0,{\delta }_1,{\delta }_1,{\delta }_3)$ by keeping all of them to be free as a generalized case. Our reconstruction technique shows that the constraints on ${\delta }_2$ (fixing ${\delta }_0$ and ${\delta }_1$) and ${\delta }_3$ (fixing ${\delta }_0$, ${\delta }_1$ and ${\delta }_2$) are almost zero for any interaction model and thus the effective scenario is well described by the linear parametrization $\delta (a)\simeq {\delta }_0+{\delta }_1(1-a)$. Additionally, a strong negative correlation between ${\delta }_0$, ${\delta }_1$ is observed independently of the dark energy fluid and the curvature of our universe.

29 pages, 13 Tables and 24 Figures; accepted for publication by Physics of the Dark Universe