Archimedean-type force in a cosmic dark fluid: III. Big Rip, Little Rip and Cyclic solutions

TL;DR

This paper investigates how an Archimedean-type force within a dark fluid model influences the Universe's fate, showing it can prevent the Big Rip but lead to a Little Rip scenario depending on the parameters.

Contribution

It introduces a self-consistent dark fluid model with an Archimedean-type force and analyzes conditions preventing the Big Rip, highlighting new interactions in dark energy and dark matter dynamics.

Findings

Archimedean-type coupling can prevent the Big Rip scenario.

The Universe may end in a Little Rip due to this interaction.

Parameter constraints are identified for avoiding catastrophic futures.

Abstract

We analyze late-time evolution of the Universe in the framework of the self-consistent model, in which the dark matter is influenced by the Archimedean-type force proportional to the four-gradient of the dark energy pressure. The dark energy is considered as a fluid with the equation of state of the relaxation type, which takes into account a retardation of the dark energy response to the Universe accelerated expansion. The dark matter is guided by the Archimedean-type force, which redistributes the total energy of the dark fluid between two its constituents, dark energy and dark matter, in the course of the Universe accelerated expansion. We focus on the constraints for the dark energy relaxation time parameter, for the dark energy equation of state parameter, and for the Archimedean-type coupling constants, which guarantee the Big Rip avoidance. In particular, we show that the Archimedean-type coupling protects the Universe from the Big Rip scenario with asymptotically infinite negative dark energy pressure, and that the Little Rip is the fate of the Universe with the Archimedean-type interaction inside the dark fluid.