Accelerated expansion from structure formation
نویسندگان
چکیده
منابع مشابه
Accelerated expansion through interaction
Interactions between dark matter and dark energy with a given equation of state are known to modify the cosmic dynamics. On the other hand, the strength of these interactions is subject to strong observational constraints. Here we discuss a model in which the transition from decelerated to accelerated expansion of the Universe arises as a pure interaction phenomenon. Various cosmological scenar...
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The present paradigm in cosmology is the usual Big-Bang Cosmology in which two stages of accelerated expansion are incorporated: the inflationary phase in the very early universe which produces the classical inhomogeneities observed in the universe, and a second stage of acceleration at the present time as the latest Supernovae observations seem to imply. Both stages could be produced by a scal...
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The fact that the ΛCDM model fits the observations does not necessarily imply the physical existence of ‘dark energy’. Dropping the assumption that cold dark matter (CDM) is a perfect fluid opens the possibility to fit the data without dark energy. For imperfect CDM, negative bulk pressure is favoured by thermodynamical arguments and might drive the cosmic acceleration. The coincidence between ...
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In braneworld models a variable vacuum energy may appear if the size of the extra dimension changes during the evolution of the universe. In this scenario the acceleration of the universe is related not only to the variation of the cosmological term, but also to the time evolution of G and, possibly, to the variation of other fundamental “constants” as well. This is because the expansion rate o...
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Braneworld theory provides a natural setting to treat, at a classical level, the cosmological effects of vacuum energy. Non-static extra dimensions can generally lead to a variable vacuum energy, which in turn may explain the present accelerated cosmic expansion. We concentrate our attention in models where the vacuum energy decreases as an inverse power law of the scale factor. These models ag...
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ژورنال
عنوان ژورنال: Journal of Cosmology and Astroparticle Physics
سال: 2006
ISSN: 1475-7516
DOI: 10.1088/1475-7516/2006/11/003