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

TL;DR

This paper explores a generalized dark sector interaction model in cosmology, analyzing its dynamics and constraints using observational data, and compares its behavior to the standard Lambda-CDM model.

Contribution

It introduces a generalized interaction framework between dark matter and dark energy, encompassing known models, and constrains it with cosmological observations.

Findings

The model fits observational data well.

The interaction affects the universe's expansion dynamics.

Thermodynamic considerations support the model's viability.

Abstract

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 is shown that for the interactions which are linear in terms the energy densities of the dark components and their first order derivatives, the net energy density 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 and the observational Hubble parameter data. 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 $\Lambda$-cold dark matter model. We further discussed the interacting scenarios taking into account the thermodynamic considerations.