Theoretical and observational bounds on some interacting vacuum energy scenarios

Understand

The dynamics of interacting dark matter-dark energy models is characterized through an interaction rate function quantifying the energy flow between these dark sectors.

• In most of the interaction functions, the expansion rate Hubble function is considered and sometimes it is argued that, as the interaction function is a local property, the inclusion of the Hubble function may influence the overall dynamics.
• This is the starting point of the present article where we consider a very simple interacting cosmic scenario between vacuum energy and the cold dark matter characterized by various interaction functions originated from a general interaction function: $Q= \Gamma\rho_{c}^{\alpha }\rho_{x}^{1-\alpha -\beta}(\rho_{c}+\rho_{x})^{\beta}$, where $\rho_c$, $\rho_x$ are respectively the cold dark matter density and vacuum energy density; $\alpha$, $\beta$ are real numbers and $\Gamma$ is the coupling parameter with dimension equal to the dimension of the Hubble rate.
• We investigate four distinct interacting cosmic scenarios and constrain them both theoretically and observationally.