Перегляд за Автор "Aller, M. F."

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  • Ескіз
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    ANALYSIS OF THE VARIABILITY AND THE SPECTRUM OF PERIODS OF EXTRAGALACTIC SOURCE OJ 287 IN THE RADIO WAVES
    (Astroprint, 2013) Donskykh, A.; Ryabov, Myhaylo I.; Sukharev, A. L.; Aller, M. F.; Рябов, Михайло Іванович
    We analyzed long-term monitoring of data flux of extragalactic source OJ 287 obtained at frequencies of 14.5 GHz (1974-2011), 8 GHz (1971-2011), 4.8GHz and (1979-2010), on the RT-26, University of Michigan, USA. Variability of the flux of the radio source was investigated by applying wavelet analysis. There were identified long-period (in the range of 3.6 to 13.6 years) and short (in the range from 1.2 to 1.8 years) components at all studied frequencies and it was determined the time of their existence. The "spectra periods" for each year of observation were built to assess the contribution of individual periods in the formation of the most powerful phase of activity of the radio source. The dynamics of the manifestations of active periods at different frequencies was observed. The obtained data was compared with the results of MOJAVE VLBI monitoring for the period of 1995-2012 years at a frequency of 15.4 GHz. It allowed to investigate the structure of emissions during periods of manifestation activity maxima.
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    Flux density evolution of the sources 3C273, 3C279 and 3C454.3 at the frequencies 102 MHz–36.8 GHz
    (2007) Volvach, A. E.; Volvach, L. N.; Larionov, M. G.; Aller, H. D.; Aller, M. F.; Yurovskiy, Yu. Yu.; Ryabov, Myhaylo I. ; Рябов, Михайло Іванович; Madrid : Consejo Superior de Investigaciones Científicas, Instituto Miguel Asín,
    The results of long-term monitoring of the sources 3C273, 3C279 and 3C454.3 at 102 MHz–36.8 GHz are presented. Numerical analysis of irregular temporal rows of the integral fluxes allowed us to detect the quasiperiodic constituents of the emission flux variations. The analysis of the parameters of binary black holes in the central regions of non-stationary objects demonstrates that these super-massive objects have an insignificant variation between the sizes of the orbits of partners, and that they are in the stage of evolution different from the time of merging by a period of less than 104 years.
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    Singular-Spectrum Analysis and Wavelet Analysis of the Variability of the Extragalactic Radio Sources 3C 120 and CTA 102
    (2016-06) Donskykh, Ganna I.; Ryabov, Myhaylo I. ; Sukharev, Artem L.; Aller, M. F.; Рябов, Михайло Іванович
    This is a study of the variability of the fluxes of radio emission from the quasar CTA 102 and the radio galaxy 3C 120 based on data from the University of Michigan Radio Astronomy Observatory (UMRAO, Ann Arbor). The data were obtained at three frequencies (14.5, 8, and 4.8 GHz) with the 26-m radio telescope. Two mutually complementary methods were used for the analysis: wavelet analysis and singular spectrum analysis. Wavelet analysis is based on the Fourier transform, while singular-spectrum analysis does not use an analyzing function. Long-duration components of the variability in the range of ~4-11 years were found for 3C 120 and ~1.5-3 years, for CTA 102. The short-duration components of the variability are characterized by periods of ~0.7-3.4 years for 3C 120 and ~0.5-0.8 years for CTA 102. These data were also compared with VLBI charts from the MOJAVE archive for studying the evolution of the components in the jets of the quasars studied here.
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    The catalog of periods of the variability of blazars 3C120, 3C273, 3C279, 3C345 and 3C454.3 at centimeter and millimeter wavelengths
    (Odessa I.I. Mechnikov National University, 2009) Volvach, A. E.; Ryabov, Myhaylo I. ; Volvach, L. N.; Sukharev, Artem L.; Aller, H. D.; Aller, M. F.; Рябов, Михайло Іванович
    ccVariations in the radio flux of 3C120, 3C273, 3C279, 3C345, 3C 454.3 are analyzed using long-term monitoring data at five frequencies from 4.8 to 36.8 GHz obtained at the University ofMichigan Radio Astronomy Observatory and the Crimean Astrophysical Observatory. A spectral analysis of the light curves at the various frequencies reveals the presence of periodic components. Using method of model calculations for each of the found period tested its ability to reproduce the observed flux variability at different frequencies. On the basis of the model calculations presented the catalog of the most reliable periods of flux variable of radio sources.
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    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.
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    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
  • Ескіз
    Документ
    VARIABILITY OF THE EXTRAGALACTIC RADIO SOURCES 3С120, СТА102, DA55 AND OJ287 ON CENTIMETER WAVES AND ITS CONNECTIONS WITH THE DATA OF VLBI OBSERVATIONS
    (Astroprint, 2012) Ryabov, Myhaylo I.; Donskykh, A.; Sukharev, A. L.; Aller, M. F.; Рябов, Михайло Іванович
    ABSTRACT. By data of the long-term monitoring (30-40 years) fluxes of extragalactic radio sources 3C120, CTA102, DA55 and OJ287 received on the RT-26, University of Michigan present results of data processing with use the wavelet analysis. Received analysis of trend and short-time components of the flux density changes in the studied frequencies 14.5, 8 and 4.8 GHz. For each time components on all frequencies found values of main periods and time of their existence, integrated power spectra for the phases activity for radio sources was built. From the results of VLBI observations in sources with long jets (3C120 and CTA102) detected quasi-periodic structures brighter components. Their appearance is linked to the dynamics of the interaction of shock waves in the jet emission from the cores. Quasi-periodic structures in the jet can be formed as a result of a return standing wave.