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Rapid Interstellar Scintillation of PKS 1257-326: Two-Station Pattern Time Delays and Constraints on Scattering and Microarcsecond Source Structure

Citation

Bignall, HE and Macquart, JP and Jauncey, DL and Lovell, JEJ and Tzioumis, AK and Kedziora-Chudczer, L, Rapid Interstellar Scintillation of PKS 1257-326: Two-Station Pattern Time Delays and Constraints on Scattering and Microarcsecond Source Structure, The Astrophysical Journal, 652, (2 I) pp. 1050-1058. ISSN 0004-637X (2006) [Refereed Article]

DOI: doi:10.1086/508406

Abstract

We report measurements of time delays of up to 8 minutes in the centimeter-wavelength variability patterns of the intrahour scintillating quasar PKS 1257-326, as observed between the VLA and the ATCA on three separate epochs. These time delays confirm interstellar scintillation as the mechanism responsible for the rapid variability, at the same time effectively ruling out the coexistence of intrinsic intrahour variability in this source. The time delays are combined with measurements of the annual variation in variability timescale exhibited by this source to determine the characteristic length scale and anisotropy of the quasar's intensity-scintillation pattern, as well as to attempt to fit for the bulk velocity of the scattering plasma responsible for the scintillation. We find evidence for anisotropic scattering and highly elongated scintillation patterns at both 4.9 and 8.5 GHz, with an axial ratio >10:1, extended in a north-west direction on the sky. The characteristic scale of the scintillation pattern along its minor axis is well determined, but the high anisotropy leads to degenerate solutions for the scintillation velocity. The decorrelation of the pattern over the baseline gives an estimate of the major-axis length scale of the scintillation pattern. We derive an upper limit on the distance to the scattering plasma of no more than 10 pc. © 2006 The American Astronomical Society. All rights reserved.

Item Details

Item Type:Refereed Article
Research Division:Physical Sciences
Research Group:Astronomical and Space Sciences
Research Field:Galactic Astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Physical Sciences
Author:Lovell, JEJ (Dr Jim Lovell)
ID Code:45340
Year Published:2006
Web of Science® Times Cited:47
Deposited By:Physics
Deposited On:2007-07-11
Last Modified:2007-07-11
Downloads:0

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