| Issue |
A&A
Volume 367, Number 3, March I 2001
|
|
|---|---|---|
| Page(s) | 770 - 779 | |
| Section | Cosmology (including clusters of galaxies) | |
| DOI | https://doi.org/10.1051/0004-6361:20000465 | |
| Published online | 15 March 2001 | |
Rapid polarization variations at 20 cm in 0917+624
1
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
2
Beijing Astronomical Observatory, National Astronomical Observatories (CAS), Beijing 100012, China
A. Witzel
Received:
15
May
2000
Accepted:
28
November
2000
The intraday variations (IDV hereafter) of the total
and the polarized flux density
observed at 20 cm in 0917+624 (in May 1989)
are analysed. It is shown that the IDV can be interpreted
in terms of refractive interstellar scintillation.
The observed variations are dominated by one scintillating component
with a timescale 
days and a scintillation
index 
. In addition,
one more scintillating
component with a shorter timescale and a smaller scintillation index
is needed to improve the fit to the observed Q- and
U-light curves. The relationship between
the scintillating components and the VLBI components
are also discussed. It is shown that Doppler beaming of
the 20 cm scintillating components with a Lorentz factor
7
may be needed to reduce their intrinsic brightness temperatures
significantly below the inverse-Compton limit.
Key words: galaxies: compact / polarization / scattering / radiation mechanisms: non-thermal / quasars: individual: 0917+62
© ESO, 2001
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