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Paper: Strong Long-Term Variability of RATAN-600 1–22 GHz Instantaneous Radio Spectra of 200 AGNs in 1997–2003
Volume: 360, AGN Variability from X-Rays to Radio Waves
Page: 137
Authors: Kovalev, Yu.A.; Kovalev, Yu.Y.
Abstract: The RATAN-600 radio telescope has been used for monitoring broad-band spectra at 5–6 wavelengths of 1.4, 2.7, 3.9, 7.7, 13, and 31 cm. About 20 spectral measurements for each of 200 sources have been made during the last 7 years. Measurements at all frequencies are made simultaneously in a time period of several minutes. The sources studied show strong variability with flux density changes of more than 50% with characteristic time scales of more than 1 month. The objects were selected from a sample of 600 objects included in the monitoring. Observed spectra are simulated by a sum of two components: the synchrotron radio emission of a continuous relativistic jet from an active core (black hole with accretion disk) in the longitudinal magnetic field applying the &lrquo;hedgehog” model of AGNs, and the optically-thin emission of an extended envelope. The long-term and short-term variability of the spectra is simulated by variability of the jet emission caused by a variable continuous flow of relativistic particles injected from the core to the jet. The model analysis yields that the nature of the radio emission and the observed behavior of variable 1–22 GHz radio spectra of various types of AGNs can be explained by the proposed relativistic jet model.
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