Abstract
In this work we explore two possible scenarios that can be considered to extend a recent proposed model by the authors known as reconstructed mimetic cosmology. This study is complemented with an statistical analysis for each case. The first scenario considers the inclusion of matter production as a possible source of cosmic expansion in the reconstructed mimetic model, at effective level was found that this construction can cross the phantom divide, the model evolves from quintessence to phantom dark energy. The second scenario corresponds to a construction of an interacting scheme for the dark sector which is described by the unified mimetic model. The resulting interaction term (not imposed by an Ansatz), Q, exhibits changes of sign leading to the violation of the second law along the cosmic evolution and non adiabaticity; the temperatures for the components of the dark sector are computed and such components are shown to be out of thermal equilibrium.
Highlights
The mimetic gravity description [1] provides a geometric origin for cold dark matter by considering that a conformal degree of freedom of gravity is encoded in an extra scalar field
The role of the Lagrange multiplier becomes relevant since enforces an important constraint for the mimetic field and besides its interpretation as emergent matter sector avoids the introduction of extra fields in the description; a first interesting feature of this model is the deviation from the standard behavior that generates the potential on the Lagrange multiplier, such deviation reveals a rich structure in the model; such kind of deviations for the matter sector are generally present in interacting models, this latter possibility was explored here
The first scenario corresponds to the inclusion of matter production effects in the mimetic description, as far as we know this is the first time that such effects are considered in the mimetic approach, these effects are expected to contribute on the cosmic expansion by means of an effective pressure; the second case corresponds to an interaction scheme for the dark sector that emerges from mimetic gravity, the mimetic scheme can be seen as an unified model for dark matter and dark energy
Summary
The mimetic gravity description [1] provides a geometric origin for cold dark matter by considering that a conformal degree of freedom of gravity is encoded in an extra scalar field. The mimetic scenario is viable to describe the early universe, the role of the mimetic scalar field and the curvature invariant in the context of loop quantum gravity is discussed in Refs. The mimetic approach was adapted for higher dimensional objects known as branes [9,10] Another interesting aspect of mimetic gravity is the avoidance of singularities during the cosmic evolution. This could be achieved by considering some conditions on the curvature scalar. The cosmic expansion for this model is not adiabatic and the the second law at present time is guaranteed only under certain conditions This interacting scenario is out of thermal equilibrium.
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