Multi-Frequency Studies Of Intrinsic Intraday Variability
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Intraday variability is detected in Blazars throughout the electromagnetic spectrum. Onlyradio emission is affected by interstellar scintillation. The characteristics of variability observedat different frequencies are often similar and suggest that intrinsic variations also contribute tothe changes detected in the radio wavelength regime. This in turn implies very high brightnesstemperatures.Unambiguous signatures of scintillation and of intrinsic changes have been identified. The propertiesof intrinsic variations are reviewed to illustrate their potential contribution to variability in theradio domain. Such intrinsic changes need to be discriminated against when studying scintillationin quasars and BL Lac objects. Observations of scintillating sources and of sources with significantintrinsic IDV suggest interesting modifications to the standard paradigm of AGN.
KeywordsBrightness Temperature Photon Density Synchrotron Emission Intrinsic Variation VLBI Observation
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