arXiv subjects

N. A. Arkhipova

Publications and source records attributed to N. A. Arkhipova.

3 recordsLinked to original sources

arXiv2001

Evolution of galaxy clusters in $Λ$MDM cosmologies

The time evolution of galaxy cluster abundance is used to constrain cosmological parameters in dark matter models containing a fraction of hot particles (massive neutrino). We test the modified MDM models with cosmic gravitational waves which are in agreement with observational data at $z=0$, and show that they do not pass the cluster evolution test and therefore should be ruled out. The models with a non-zero cosmological constant are in better agreement with the evolution test. We estimate $Ω_Λ$ and find that it is strongly affected by a small fraction of hot dark matter: $0.4 <Ω_Λ<0.8$ for $Ω_H /Ω_M <0.2$.

astro-ph↗

arXiv2000

Current status of cosmological MDM model

An analysis of cosmological models in spatially flat Friedmann Universe with cosmic gravitational wave background and zero $Λ$-term is presented. The number of free parameters is equal to 5, they are $σ_8$, $n$, $Ω_ν$, $Ω_b$, and $h$. The normalization of the spectrum of density perturbations on galaxy cluster abundance ($σ_8 = 0.52\pm 0.04$) has been used to calculate numerically the value of the large scale CMB anisotropy ($\ell\simeq 10$) and the relative contribution of cosmological gravitational waves T/S. Increasing $Ω_ν$ weaken the requirements to the value of T/S, however even for $Ω_ν\le 0.4$ the models with $h+n\ge 1.5$ suggest considerable abundance of gravitational waves: T/S${}^>_\sim 0.3$. In models with $Ω_ν\le 0.4$ and scale-invariant spectrum of density perturbations ($n=1$): T/S${}^>_\sim 10(h-0.47)$. Minimization of the value T/S is possible only in the range of the red spectra ($n<1$) and small $h$ ($<0.6$). It is shown that the models with T/S$\in [0, 3]$ admit both moderate red and blue spectra of density perturbations, $n\in[0.9,1.2]$, with rather high abundance hot dark matter, $Ω_ν\in [0.2,0.4]$. Any condition, $n<0.9$ or $Ω_ν<0.2$, decreases the relative amplitude of the first acoustic peak for more than 30% in comparison with its hight in the standard CDM normalized by COBE data.

astro-ph↗

arXiv1998

Observational Constraints for Power-law spectra of Density Perturbations

We present an analysis of cosmological models with mixed dark matter (spectrum slope of density perturbations $n_S \in [0.6, 1.6]$, hot dark matter abundance $Ω_ν\in [0.0, 0.6]$) in spatially flat Universe, based on Press-Schechter formalism (P\&S). We found that the models with $n_S > 1$ and $Ω_ν< 0.5$ are preferable. Additionally, for all considered models we simulated $ΔT/T\vert_{10^0}$ and compared it with the COBE measured amplitude of CMB anisotropy. We found that the models favourable for galaxy cluster abundance need large amount of cosmological gravitational waves (T/S $> 1$).

astro-ph↗