Milliarcsecond Structure of Microarcsecond Sources
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Date
2007-06-12
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Citation of Original Publication
Ojha, Roopesh; Lazio, T. Joseph W.; Fey, Alan L.; Jauncey, David L.; Lovell, James E. J.; Johnston, Kenneth J.; Milliarcsecond Structure of Microarcsecond Sources; Bursts, Pulses and Flickering:Wide-field monitoring of the dynamic radio sky (2007); https://pos.sissa.it/056/017/pdf
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Abstract
We present the key findings of an ongoing program of Very Long Baseline Interferometry (VLBI) observations of scintillating and non-scintillating flat-spectrum extragalactic radio sources whose scintillation status was determined by the Micro-Arcsecond Scintillation-Induced Variability (MASIV) survey. Both single frequency (8.4 GHz) observations to compare morphologies, and multi-frequency observations (from 330 MHz through 22 GHz) to study scattering behaviour have been carried out. Though scintillation probes the structure of quasars on scales of tens of microarcseconds, information at the milliarcsecond scale probed by these VLBI observations is proving invaluable in furthering our understanding of this phenomenon. Also, the common occurence of scintillation in compact radio sources might be the ultimate limitation for VLBI astrometry (which among other things defines the International Celestial Reference Frame) in the sense that the final precision of reference frame source positions are likely to be influenced by the presence of scintillation.