1,118 research outputs found
Dark Energy and Large-Scale Structure of the Universe
The evolution of matter density perturbations in two-component model of the
Universe consisting of dark energy (DE) and dust-like matter (M) is considered.
We have analyzed it for two kinds of DE with : a) unperturbed
energy density and b) perturbed one (uncoupled with matter). For these cases
the linear equations for evolution of the gauge-invariant amplitudes of matter
density perturbations are presented. It is shown that in the case of
unperturbed energy density of DE the amplitude of matter density perturbations
grow slightly faster than in the second case.Comment: 4 pages, 1 figure, submitted to the proceedings of international
conference "Astronomy in Ukraine - Past, Present, Future", July 15-17, Kiev,
Ukrain
Non-linear power spectra of dark and luminous matter in halo model of structure formation
The late stages of large-scale structure evolution are treated
semi-analytically within the framework of modified halo model. We suggest
simple yet accurate approximation for relating the non-linear amplitude to
linear one for spherical density perturbation. For halo concentration
parameter, , a new computation technique is proposed, which eliminates the
need of interim evaluation of the . Validity of the technique is
proved for CDM and WDM cosmologies. Also, the parameters for
Sheth-Tormen mass function are estimated. The modified and extended halo model
is applied for determination of non-linear power spectrum of dark matter, as
well as for galaxy power spectrum estimation. The semi-analytical techniques
for dark matter power spectrum are verified by comparison with data from
numerical simulations. Also, the predictions for the galaxy power spectra are
confronted with 'observed' data from PSCz and SDSS galaxy catalogs, good
accordance is found.Comment: 18 pages, 8 figures; major changes from the previous version;
accepted for publivation in Phys. Rev.
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