Перегляд за Автор "Donskykh, G. I."

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  • Ескіз
    Документ
    The study of extragalactic sources 3C 446 AND 3C 345 with using the singular spectrum and wavelet analysis
    (Одеський національний університет імені І. І. Мечникова, 2015) Donskykh, G. I.; Ryabov, Myhaylo I.; Sukharev, A. L.; Aller, M. F.; Рябов, Михайло Іванович
    We investigated the data of monitoring of flux density of extragalactic sources 3С446 and 3C345, which was held on 26-meter radio telescope of University of Michigan at frequencies 14.5, 8 and 4.8 GHz. The data of observations were investigated using singular spectrum analysis and wavelet-analysis. According to the results of wavelet analysis for each year of observations, graphics of “spectra periods” were built to determine the contribution of individual periods in the activity of the radio source. The results obtained with two different methods showed a good correlation between them. For a long time component of the flux the periods of ~ 5 – 9 years were found. For short term components the periods of ~ 1 – 4 years are presented. The results obtained using two different methods were compared with VLBI radio maps, which were obtained by the program MOJAVE. The changes of periods over time are associated with certain physical processes in the system "core – accretion disk – jet" and with appearing of new bright components (knots) in the jet.
  • Ескіз
    Документ
    Using the methods of wavelet analysis and singular spectrum analysis in the study of radio source BL Lac
    (Astroprint, 2014) Donskykh, G. I.; Ryabov, Myhaylo I.; Sukharev, A. L.; Aller, M. F.; Рябов, Михайло Іванович
    We investigated the monitoring data of extragalactic source BL Lac. This monitoring was held with University of Michigan 26-meter radio telescope. To study flux density of extragalactic source BL Lac at frequencies of 14.5, 8 and 4.8 GHz, the wavelet analysis and singular spectrum analysis were used. Calculating the integral wavelet spectra allowed revealing long-term components (~7-8 years) and short-term components (~ 1-4 years) in BL Lac. Studying of VLBI radio maps (by the program Mojave) allowed investigating features of components movement relatively to the VLBI core. The data of radio astronomy observations were also investigated using singular spectrum analysis. This method can solve the task of allocating trend, detection of periodic components and band-pass filtering (reconstruction of time series from quantity of main components, the last corresponds to individual bands of periods on time-frequency spectra or Fourier spectra). Singular spectrum analysis does not use the analyzing function, so its calculations allow to distinguish various components of investigated series with a high accuracy. To get spectral power distribution depending on time in the studied narrowband components obtained by singular spectrum analysis, short-term Fourier transformation was used