Milliarcsecond Structure of Microarcsecond Sources: Comparison of Scintillating and Nonscintillating Extragalactic Radio Sources

Author/Creator ORCID

Date

2004-10-20

Department

Program

Citation of Original Publication

Ojha Roopesh, Fey Alan L, Jauncey David L, Lovell James E. J, Johnston Kenneth J,Milliarcsecond Structure of Microarcsecond Sources: Comparison of Scintillating and Nonscintillating Extragalactic Radio Sources, Vol 614 #2, https://iopscience.iop.org/article/10.1086/423797

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Public Domain Mark 1.0
This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law

Subjects

Abstract

We compare the milliarcsecond-scale morphology of scintillating and nonscintillating sources. The scintillating sources are drawn from those flat-spectrum extragalactic radio sources discovered, by the Micro-Arcsecond Scintillation-Induced Variability Survey, to have flux density variability at 5 GHz on timescales from hours to days. Intrinsic source structure information is obtained from previously published and/or publicly available 8.4 GHz Very Long Baseline Array images. A sample of low flux density (Sν=5 GHz < 0.3 Jy) scintillating sources was compared with a sample of high flux density (Sν=5 GHz ~ 1 Jy) scintillators, as well as a sample of high flux density nonscintillators. All source samples meet the selection criteria of the Micro-Arcsecond Scintillation-Induced Variability Survey, thus ensuring that all three source samples are suitable for comparative study. We find that all scintillating sources (both low and high flux density samples) are significantly more core dominated than nonscintillating sources. Further, the overall source size of the scintillating sources is significantly smaller than that of nonscintillators. There does not appear to be any significant difference between the milliarcsecond-scale morphologies of low and high flux density scintillators. These results demonstrate that it is the core of the radio source that is scintillating.