Determination of Ω_Λand H_0 from photometric data of radio galaxies

Abstract

From photometric observations of elliptical galaxies, among which are both radio galaxies and radio-quiet objects, an investigation was carried out of the relationship `redshift -- age of the stellar system' $(Δz/Δt)$. By means of this relationship cosmological parameters $H(z)$ and $Ω_Λ$ are estimated. Ages of stellar systems are determined within the framework of evolution models of synthetic spectra PEGASE and GISSEL. This approach can be considered as time study of objects of the early Universe independent of other cosmological models. Construction of a pooled sample is described, containing 220 objects from different populations of elliptical galaxies, for which an analysis of the upper limit of the age of formation of a stellar system was performed. These data were used to estimate the boundaries of determination of the cosmological parameters $H_0$ and $Λ$--term: $H_0=72\pm10$ and $Ω_Λ=0.8\pm0.1$ in the model GISSEL and $H_0=53\pm10$, and $Ω_Λ=0.8\pm0.1$ in the model PEGASE.