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

Journal Article · Fri Jul 01 04:00:00 EDT 2016 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2016/07/050· OSTI ID:22679592

Bouhmadi-López, Mariam; Kumar, K. Sravan; Marto, João ^[1]; Morais, João ^[2]; Zhuk, Alexander ^[3]

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1. Departamento de Física, Universidade da Beira Interior, Rua Marquês D'Ávila e Bolama, 6201-001 Covilhã (Portugal)
2. Department of Theoretical Physics, University of the Basque Country UPV/EHU, P.O. Box 644, 48080 Bilbao (Spain)
3. Astronomical Observatory, Odessa National University, Street Dvoryanskaya 2, Odessa 65082 (Ukraine)

In this paper, we consider the Universe at the late stage of its evolution and deep inside the cell of uniformity. At these scales, we can consider the Universe to be filled with dust-like matter in the form of discretely distributed galaxies, a K -essence scalar field, playing the role of dark energy, and radiation as matter sources. We investigate such a Universe in the mechanical approach. This means that the peculiar velocities of the inhomogeneities (in the form of galaxies) as well as the fluctuations of the other perfect fluids are non-relativistic. Such fluids are designated as coupled because they are concentrated around the inhomogeneities. In the present paper, we investigate the conditions under which the K -essence scalar field with the most general form for its action can become coupled. We investigate at the background level three particular examples of the K -essence models: (i) the pure kinetic K -essence field, (ii) a K -essence with a constant speed of sound and (iii) the K -essence model with the Lagrangian bX + cX {sup 2}− V (φ). We demonstrate that if the K -essence is coupled, all these K -essence models take the form of multicomponent perfect fluids where one of the component is the cosmological constant. Therefore, they can provide the late-time cosmic acceleration and be simultaneously compatible with the mechanical approach.

• OSTI ID: 22679592
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 07 Vol. 2016; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCELERATION
COSMIC DUST
COSMOLOGICAL CONSTANT
COSMOLOGICAL MODELS
EVOLUTION
FLUCTUATIONS
GALAXIES
IDEAL FLOW
LAGRANGIAN FUNCTION
NONLUMINOUS MATTER
RELATIVISTIC RANGE
SCALAR FIELDS
SOUND WAVES
UNIVERSE
VELOCITY