41 research outputs found

    Coupled DM heating in SCDEW cosmologies

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    Strongly Coupled Dark Energy plus Warm dark matter (SCDEW) cosmologies admit the stationary presence of ∼1 %\sim 1\, \% of coupled-DM and DE, since inflationary reheating. Coupled-DM fluctuations therefore grow up to non-linearity even in the early radiative expansion. Such early non-linear stages are modelized here through the evolution of a top-hat density enhancement, reaching an early virial balance when the coupled-DM density contrast is just 25-26 and DM density enhancement is ∼10 % \sim 10\, \% of total density. During the time needed to settle in virial equilibium, the virial balance conditions however continue to modify, so that "virialized" lumps undergo a complete evaporation. Here we outline that DM particles processed by overdentities preserve a fraction of their virial momentum. Although fully non-relativistic, the resulting velocities (moderately) affect the fluctuation dynamics over greater scales, entering the horizon later on.Comment: 20 pages, 7 figures; updated to match the published versio

    Dark Matter, Dark Energy and the solution of the strong CP problem

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    The strong CP problem was solved by Peccei & Quinn by introducing axions, a viable candidate for Dark Matter (DM). Here the PQ approach is modified so to yield also Dark Energy (DE). DM and DE arise, in fai proportions, from a single scalar field, without tuning any extra parameter. In the present epoch, they are weakly coupled. Fluctuations have a fair evolution. The model is also fitted to the WMAP1 release, using a Markov Chain Monte Carlo technique, and performs as well as Λ\LambdaCDM, coupled or uncoupled DE. Best--fit cosmological parameters for different models are mostly within 2--σ\sigma level. Here, the main peculiarity of the model is to favor high values of the Hubble parameter.Comment: Proceeding of the workshop dsu2006, "The Dark Side of th Universe", Madrid, June 20-24, 200
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