Shepelyev V. Angular structure of extragalactic radio sources by the results of interferometer observations in the decameter range of radio waves

The object of the study: the radio emission of extragalactic radio sources associated with galactic nuclei activity ; the purpose: determination of the angular structure of extragalactic radio sources in the decameter range of wavelengths, the elucidation of the causes of its change with a frequency reduction, determination of the effect of space plasma on the sources structure; the methods applied: experimental determination of the visibility function using VLBI, modeling of the angular brightness distribution with arbitrary oriented elliptic components with Gaussian brightness distribution. The new results are following. The method of interferometer calibration and visibility measurements has been improved. The procedure of model fitting of angular brightness distribution with visibility modules has been designed for the case of poor UV-plane covering. Models of angular brightness distribution for some radio galaxies and quasars have been first obtained. It has been established, the main causes of changes of the sources angular structure in the range are: deflection spectra of their components from the power law in consequence of synchrotron self-absorption in nucleus and hot spots and reduction of synchrotron losses in lobes, appearance of extended halos with steep spectrum and low surface brightness, expansion of lobes of the radio galaxies. The spectral index of injection and synchrotron age of the radio sources or their components has been defined. The field of application: construction of new instruments for low frequency radio astronomy, development of models of generation and evolution of radio sources.