Abstract
Physical limits on the equation-of-state (EoS) parameter of a dark energy component non-minimally coupled with the dark matter field are examined in light of the second law of thermodynamics and the positiveness of entropy. Such constraints are combined with observational data sets of type Ia supernovae, baryon acoustic oscillations and the angular acoustic scale of the cosmic microwave background to impose restrictions on the behaviour of the dark matter/dark energy interaction. Considering two EoS parameterisations of the type w = w_0 + w_azeta (z), we derive a general expression for the evolution of the dark energy density and show that the combination of thermodynamic limits and observational data provide tight bounds on the w_0 - w_a parameter space.
Highlights
The physical mechanism behind the late-time cosmic acceleration is currently one of the major open problems in the field of cosmology
Using the approach of [38,39] to obtain the interaction term, we derive the evolution of dark energy density for two equation-of-state (EoS) parameterisations of the type w = w0 + waζ (z) [40,41,42] and impose physical constraints on its parameters from both the second law of thermodynamics and the positiveness of entropy
We show that the usual constraints on the w0 − wa parametric space are significantly enhanced when the thermodynamic bounds are incorporated in the observational analysis
Summary
The physical mechanism behind the late-time cosmic acceleration is currently one of the major open problems in the field of cosmology This phenomenon has been evidenced from analysis and interpretation of different observational data sets [1,2,3,4,5,6,7,8,9] and, in the context of the general relativity theory, can be explained either if one admits the existence of an exotic field, the so-called dark energy, or if the matter content of the universe is subject to dissipative processes [10,11] (see [12,13,14] for a review).
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