Astronomical bounds on a cosmological model allowing a general interaction in the dark sector [CEA]

Non-gravitational interaction between two barotropic dark fluids, namely the pressureless dust and the dark energy in a spatially flat Friedmann-Lema\^{i}tre-Robertson-Walker model has been discussed. It has been established that for the interactions which are linear in terms the energy densities of the dark components and their first order derivatives, the evolution is governed by a second order differential equation with constant coefficients. Taking a generalized interaction, which includes a number of already known interactions as special cases, the dynamics of the universe is described for three types of the dark energy equation of state, namely that of interacting quintessence, interacting vacuum energy density and interacting phantom. The models have been constrained using the standard cosmological probes, Supernovae type Ia data from joint light curve analysis, the observational Hubble parameter data, baryon acoustic oscillation distance measurements and the cosmic microwave background shift parameter. Two geometric tests, the cosmographic studies and the $Om$ diagnostic have been invoked so as to ascertain the behaviour of the present model vis-a-vis the $\Lambda$CDM model. We further discussed the interacting scenarios taking in the context of the thermodynamic considerations.

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S. Pan, A. Mukherjee and N. Banerjee
Wed, 11 Oct 17

Comments: 24 pages, 17 captioned figures, 4 tables