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Broad-band Radio Spectra Variability of 550 AGN in 1997-2001

Published online by Cambridge University Press:  05 March 2013

Y. Y. Kovalev ,
Yu A. Kovalev ,
N. A. Nizhelsky  and
A. B. Bogdantsov
Y. Y. Kovalev*
Affiliation:
Astro Space Center of P. N. Lebedev Physical Institute, Profsoyuznaya 84/32, Moscow, 117997 Russia
Yu A. Kovalev
Affiliation:
Astro Space Center of P. N. Lebedev Physical Institute, Profsoyuznaya 84/32, Moscow, 117997 Russia
N. A. Nizhelsky
Affiliation:
Special Astrophysical Observatory, Nizhny Arkhyz, KChR, 357147 Russia
A. B. Bogdantsov
Affiliation:
Special Astrophysical Observatory, Nizhny Arkhyz, KChR, 357147 Russia
*
[email protected]
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Abstract

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Results are presented of long-term monitoring at the radio telescope RATAN–600 and a model interpretation of instantaneous 1–22 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 −30° to +43°. 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–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.

Keywords

galaxies: activegalaxies: jetsBL Lacertae objects: generalquasars: generalradio continuum: galaxies
Type
Research Article
Information
Publications of the Astronomical Society of Australia , Volume 19 , Issue 1 , 2002 , pp. 83 - 87
Copyright
Copyright © Astronomical Society of Australia 2002

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