Intraday Variability in Northern Hemisphere Radio Sources

Abstract

We summarize results from flux density monitoring campaigns performed with the 100 meter radio-telescope at Effelsberg and the VLA during the past 15 yrs. We briefly discuss some of the statistical properties of the rapid variability from now more than 40 high declination sources, which show Intraday Variability (IDV). In general, IDV is more pronounced for sources with flat radio spectra and compact VLBI structures. The frequency dependence of the variability pattern varies with source and observing time. For 0917+62, we present new VLBI images, which suggest that the variability pattern is modified by the occurrence of new jet components. For 0716+71, we show the first detection of IDV at millimeter wavelengths (32 GHz). For the physical interpretation of the IDV phenomenon, a complex source and frequency dependent superposition of interstellar scintillation and source intrinsic variability should be considered.

8 pages, 4 figures, to appear in: `AGN Variability Across the Electromagnetic Spectrum', a conference held at CSIRO, Sydney, 25-29 June 2001. To be published by PASA

References in corpus (3)

• Multi-Epoch VLBA Observations of EGRET-Detected Quasars and BL Lac Objects: Superluminal Motion of Gamma-Ray Bright Blazars
• Annual modulation in IDV of quasar 0917+624 due to Interstellar Scintillation
• Intra-Day Variability and the Interstellar Medium Towards 0917+624

Cited by in corpus (21)

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• Multiwavelength Intraday Variability of the BL Lac S5 0716+714
• The IDV source J1128+5925, a new candidate for annual modulation?
• Space-VLBI Polarimetry of the BL Lac Object S5 0716+714: Rapid Polarization Variability in the VLBI core
• Annual Modulation in the Variability Properties of the IDV-Source 0917+624 ?
• The Micro-Arcsecond Scintillation-Induced Variability (MASIV) Survey III. Optical Identifications and New Redshifts
• Optical and Radio Variability of BL Lacertae
• High Resolution Radio Astronomy Using Very Long Baseline Interferometry
• Two-year monitoring of intra-day variability of quasar 1156+295 at 4.8 GHz
• Generalized Langevin equation with colored noise description of the stochastic oscillations of accretion disks
• Intra-day variability observations and the VLBI structure analysis of quasar S4 0917+624
• Very Long Baseline Array observations of the Intraday Variable source J1128+592
• Power Spectral Distribution of the BL Lacertae Object S5 0716+714
• The brightness temperature problem in extreme IDV quasars: a model for PKS 0405-385
• J1128+592: a highly variable IDV source
• High frequency VLBI observations of the scatter broadened quasar B2005+403
• Appearance of an accretion disk perturbed by fractional Brownian Motion density
• IDV Observations & Study of the Quasar 0917+624
• The Size of IDV Jet Cores
• Kinematic studies of the IDV quasar 0917+624