Annual modulation in the scattering of J1819+3845: peculiar plasma velocity and anisotropy

Abstract

We present two years of monitoring observations of the extremely variable quasar J1819+3845. We observe large yearly changes in the timescale of the variations (from ~ 1 hour to ~ 10 hours at 5GHz). This annual effect can only be explained if the variations are caused by a propagation effect, and thus affected by the Earth's relative speed through the projected intensity pattern. To account for this effect, the scattering plasma must have a transverse velocity with respect to the local standard of rest. The velocity calculated from these observations is in good agreement with that obtained from a two telescope delay experiment (Dennett-Thorpe & de Bruyn 2001). We also show that either the source itself is elongated, or that the scattering plasma is anisotropic, with an axial ratio of >6:1. As the source is extended on scales relevant to the scattering phenomenon, it seems plausible that the anisotropy is due to the source itself, but this remains to be investigated. From the scintillation characteristics we find that the scattering material is a very strong, thin scatterer within ~ten parsecs. We determine a source size at 5GHz of 100 to 900microarcsecs, and associated brightness temperatures of 10^{10} to 10^{12}K.

Accepted for publication in A&A

References in corpus (12)

• The emission line - radio correlation for radio sources using the 7C Redshift Survey
• Compressible MHD Turbulence in Interstellar Plasmas
• Composite Spectra from the FIRST Bright Quasar Survey
• The discovery of a microarcsecond quasar: J1819+3845
• PKS 0405--385: the smallest radio quasar?
• Interstellar scintillation as the origin of rapid radio variability in the quasar J1819+3845
• Anisotropic Scattering of OH/IR Stars Towards the Galactic Center
• Annual modulation in IDV of quasar 0917+624 due to Interstellar Scintillation
• Origin of the viewing-angle dependence of the optical continuum emission in quasars
• Intra-Day Variability and the Interstellar Medium Towards 0917+624
• Interstellar Scintillation od Pulsar B0809+74
• Radio-wave propagation through a medium containing electron-density fluctuations described by an anisotropic Goldreich-Sridhar spectrum

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