Publications of the MPIfR
Optical & Infrared
Interferometry Group
Qian, Shan-Jie; Krichbaum, T. P.;
Zhang, Xi-Zhen; Fuhrmann, L.; Cimò, G.; Kraus, A.; Beckert, T.;
Britzen, S.; Witzel, A.; Zensus, J. A.
Refractive Focusing by Interstellar Clouds and
the Rapid Polarization Angle Swing in QSO 1150+812
Chinese Journal of Astronomy and Astrophysics,
Volume 6, Issue 1, pp. 1-14 (2006)
Abstract
A very rapid polarization position angle swing of ~180° (with a time
scale of ~6 hours) observed at 2 cm in QSO 1150+812 (z = 1.25) was
reported by Kochenov & Gabuzda. This very rare event is difficult
to explain. We found a possible interpretation in the framework of a
source model consisting of three polarized components, in which two
compact polarized components are nearly simultaneously occulted by an
interstellar cloud, with consequent focusing-defocusing effects. A
specific plasma-lens model is proposed which can reasonably fit the
polarized flux density curve with results derived for the two lensed
components. Some physical parameters of the plasma-lens and the source
components are estimated. The two compact polarized components are
estimated to have brightness temperatures of ~6×1012 K. Thus a bulk
relativistic motion with a Lorentz factor less than 10 is required to
meet the inverse–Compton limit.
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