Coupled scalar fields in the late Universe: the mechanical approach and the late cosmic acceleration
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Дата
2016-09-28
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Видавець
IOP Publishing Ltd and Sissa Medialab srl
Анотація
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 consider the Universe to be filled with dustlike matter in the form of discretely distributed galaxies, a minimally coupled scalar field 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 fluctuations of other perfect fluids are non-relativistic. Such fluids are designated as coupled because they are concentrated around inhomogeneities. In the present paper we investigate the conditions under which a scalar field can become coupled, and show that, at
the background level, such coupled scalar field behaves as a two component perfect fluid: a network of frustrated cosmic strings with EoS parameter w = −1/3 and a cosmological constant. The potential of this scalar field is very flat at the present time. Hence, the coupled scalar field can provide the late cosmic acceleration. The fluctuations of the energy density and pressure of this field are concentrated around the galaxies screening their gravitational potentials. Therefore, such scalar fields can be regarded as coupled to the inhomogeneities.
Опис
Ключові слова
cosmic flows, cosmological perturbation theory, dark energy theory, gravity
Бібліографічний опис
Journal of Cosmology and Astroparticle Physics