Investigation of Spectral and Time Behavior of Radio Emission Fluxes of Active Galaxy and Quasar Nuclei at Different Phases of their Activity

Abstract

Data on almost 40-year monitoring programs carried out with the 26-m radio telescope of the University of Michigan Radio Astronomical Observatory on frequencies 14.5 GHz (1974-1999), 8 GHz (1966-1999) and 4.8 GHz (1978-1999) were used for improvement of the detection of spectral and time features of changing fluxes radiation of radio-sources 3С273, 3С279 and 3С454.3. The handling procedure is applied that sequentially permits to tap periods of variability of fluxes from those most durable to the shortest ones. The long-term variability periods of fluxes for 3С273 were 7-8 and 11 years, 3С279 3-6 and 12 years, 3С454.3 6 and 12 years. Yet a lot of periods at all frequencies in an interval from 3 to 0.6 years is found. Separate periods of activity for each source simultaneously observed at three frequencies were investigated. In each activity period the growth-phases of a flux, maximum and minimum phases and intermediate extremums were found. It is shown that in each activity period the time lags of variability fluxes between neighboring pairs of frequencies were different for different activity phases. Thus they varied for 3С273 from 0.1 to 2.5 years, 3С279 from 0 to 0.7 years, 3С454.3 from 0 to 0.5 years.