
%0 Journal Article
%A Kovalev, Y. Y. 
%A Kovalev, Yu A. 
%A Nizhelsky, N. A. 
%A Bogdantsov, A. B. 
%T Broad-Band Radio Spectra Variability of 550 AGN in 1997-2001
%J Publications of the Astronomical Society of Australia
%D 2002/06/28
%V 19
%N 1
%P 83-87
%K galaxies: active &#8212; galaxies: jets &#8212; BL Lacertae objects: general &#8212; quasars: general &#8212; radio continuum: galaxies
%R https://doi.org/10.1071/AS01109
%U https://www.publish.csiro.au/paper/AS01109 
%X Results are presented of long-term monitoring at the radio telescope RATAN&#8211;600 and a model interpretation of instantaneous 1&#8211;22 GHz spectra at six frequencies for a sample of 550 compact extragalactic radio sources. The sources are selected from the Preston et al. (1985) VLBI survey and are located in the declination range from &#8722;30&#176; to +43&#176;. Dependence of the index of variability on frequency is analysed for different subsamples. Factors of flux density variations range from 1 to 15. A typical behaviour of spectra evolution during strong radio outbursts in various objects is recognised suggesting a common physical nature of the variability. Invoking VLBI observations in spectra&#8211;structure analysis, we find that usually more than 70% of the total emission is coming from the mas scale at frequencies higher than 5 GHz. The observed variability can be explained in the model with a relativistic jet of parsec scale in the longitudinal magnetic field or in the shock-in-jet model. 
