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Scientific achievements, Metagalaxy sector

Within the "Big Trio" program (RATAN-600 - VLA - 6-m BTA telescope) 30 objects were identified from a sub-sample of SS RC sources. A vast majority of these sources are powerful radio galaxies with redshifts exceeding 1, where the average (photometric) redshift amounts to Z~2. Apparently, they are associated with giant elliptical galaxies of the first generation.

Using the two-dimensional spectroscopy method, the observations of NGC4151, 3516, 5548, 6814 galaxies were carried out with high angular (~1") and spectral (~30km/s) resolution. It was demonstrated that in NGC4151 the observed noncircular gas velocities are related to the motions in the field of nonaxisymmetric potential. In the perinuclear region of NGC3516 a gelical structure emitting in the [OIII] line was detected.

Based on the results of spectrophotometric observations with a high signal-to-noise ratio of 15 blue compact galaxies with low abundances of elements heavier than helium, the origin of nitrogen in these objects was investigated. It was found that for 8 galaxies with the lowest metallicities (O/H from 1/40 to 1/10 of solar metallicity) the nitrogen to oxygen abundance ratio is low and constant within a small variance (log(N/O)=-1.58±0.02). These data can be explained neither by the secondary origin of nitrogen, nor by a delay in generation of the primary nitrogen in the intermediate-mass stars. The only possible explanation of the obtained observational data is a model of chemical evolution with the primary generation of both oxygen and nitrogen inside the same massive stars.

Based on the high-accuracy spectrophotometric observations of 10 blue compact galaxies with a low abundance of elements, the most precise value of the mass fraction of helium Y(p) was obtained. The value of the primary helium mass fraction for the given galaxies is Y(p) = 0.233±0.003. This value, being the most accurate up to date, is in good agreement with a lower limit Y(p) = 0.236, yielded within the standard picture of the Big Bang nucleosynthesis. The slope of the dY/dZ = 5.8±1.7 dependence is significantly steeper than the one predicted by the simple closed-box (CB) models of chemical evolution, but it corresponds to the prediction of models, based on the selective galactic wind.

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