English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

In this paper, we consider the Universe at the late stage of its evolutionand deep inside the cell of uniformity. At these scales, we can consider theUniverse to be filled with dust-like matter in the form of discretelydistributed galaxies, a $K$-essence scalar field, playing the role of darkenergy, and radiation as matter sources. We investigate such a Universe in themechanical approach. This means that the peculiar velocities of theinhomogeneities (in the form of galaxies) as well as the fluctuations of theother perfect fluids are non-relativistic. Such fluids are designated ascoupled because they are concentrated around the inhomogeneities. In thepresent paper, we investigate the conditions under which the $K$-essence scalarfield with the most general form for its action can become coupled. Weinvestigate at the background level three particular examples of the$K$-essence models: (i) the pure kinetic $K$-essence field, (ii) a $K$-essencewith a constant speed of sound and (iii) the $K$-essence model with theLagrangian $bX+cX^2-V(\phi)$. We demonstrate that if the $K$-essence iscoupled, all these $K$-essence models take the form of multicomponent perfectfluids where one of the component is the cosmological constant. Therefore, theycan provide the late-time cosmic acceleration and be simultaneously compatiblewith the mechanical approach.

$K$-essence model from the mechanical approach point of view: coupled scalar field and the late cosmic acceleration