242 research outputs found
Recovery of fluctuation spectrum evolution from tomographic shear spectra
Forthcoming large angle surveys are planned to obtain high precision
tomographic shear data. In principle, they will allow us to recover the spectra
of matter density fluctuation, at various redshift, through the inversion of
the expressions yielding shear from fluctuation spectra. This was discussed in
previous work, where SVD techniques for matrix inversion were also shown to be
the optimal tool to this aim. Here we show the significant improvements
obtainable by using a 7 bin tomography, as allowed by future Euclid data, as
well as the question of error propagation from shear to fluctuation spectra. We
find that the technique is a promising tool, namely for the analysis of baryon
physics throug high-l shear spectra and to test the consistency between
expansion rate and fluctuation growth.Comment: 22 pages, 10 figure
Coupled DM heating in SCDEW cosmologies
Strongly Coupled Dark Energy plus Warm dark matter (SCDEW) cosmologies admit
the stationary presence of 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 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
Mixed Dark Matter from Axino Distribution
We study the possibility of mixed dark matter obtained through the phase
space distribution of a single particle. An example is offered in the context
of SUSY models with a Peccei-Quinn symmetry. Axinos in the 100 keV range can
naturally have both thermal and non-thermal components. The latter one arises
from the lightest neutralino decays and derelativizes at z ~ 10^4.Comment: Figures added, references fixed. Version accepted for publication on
Phys. Rev. D. LaTeX. 9 pages, 3 figures, uses epsfig.st
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