Microarcsecond Radio Imaging using Earth Orbit Synthesis

Abstract

The observed interstellar scintillation pattern of an intra-day variable radio source is influenced by its source structure. If the velocity of the interstellar medium responsible for the scattering is comparable to the earth's, the vector sum of these allows an observer to probe the scintillation pattern of a source in two dimensions and, in turn, to probe two-dimensional source structure on scales comparable to the angular scale of the scintillation pattern, typically $\sim 10\mu$as for weak scattering. We review the theory on the extraction of an ``image'' from the scintillation properties of a source, and show how earth's orbital motion changes a source's observed scintillation properties during the course of a year. The imaging process, which we call Earth Orbit Synthesis, requires measurements of the statistical properties of the scintillations at epochs spread throughout the course of a year.

ApJ in press. 25 pages, 7 figs

References in corpus (5)

• Interstellar scintillation as the origin of rapid radio variability in the quasar J1819+3845
• Annual modulation in IDV of quasar 0917+624 due to Interstellar Scintillation
• The ATCA Intraday Variability Survey of Extragalactic Radio Sources
• Intra-Day Variability and the Interstellar Medium Towards 0917+624
• Radio-wave propagation through a medium containing electron-density fluctuations described by an anisotropic Goldreich-Sridhar spectrum

Cited by in corpus (9)

• Rapid Variability and Annual Cycles in the Characteristic Time-scale of the Scintillating Source PKS 1257-326
• The Micro-Arcsecond Scintillation-Induced Variability (MASIV) Survey II: The First Four Epochs
• Rapid interstellar scintillation of PKS B1257-326: two-station pattern time delays and constraints on scattering and microarcsecond source structure
• The IDV source J1128+5925, a new candidate for annual modulation?
• The MASIV Survey IV: relationship between intra-day scintillation and intrinsic variability of radio AGNs
• Scintillation in the Circinus Galaxy water megamasers
• Annual Cycles in the Interstellar Scintillation Timescales of PKS B1519-273 and PKS B1622-253
• Interstellar Scintillation of an Extreme Scintillator: PKS B1144-379
• Observations of Intrahour Variable Quasars: Scattering in our Galactic Neighbourhood