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Multifrequency Polarization Variations in 0917+624

Published online by Cambridge University Press:  12 April 2016

S.J. Qian ,
A. Kraus ,
T.P. Krichbaum ,
A. Witzel  and
J.A. Zensus
S.J. Qian
Affiliation:
Max-Planck-Institut für Radioastronomie, Bonn, Germany
A. Kraus
Affiliation:
Max-Planck-Institut für Radioastronomie, Bonn, Germany
T.P. Krichbaum
Affiliation:
Max-Planck-Institut für Radioastronomie, Bonn, Germany
A. Witzel
Affiliation:
Max-Planck-Institut für Radioastronomie, Bonn, Germany
J.A. Zensus
Affiliation:
Max-Planck-Institut für Radioastronomie, Bonn, Germany

Abstract

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Intraday variability in compact flat-spectrum radio sources has been intensively studied in recent years. For most IDV events the apparent brightness temperatures derived from the observed timescales are in the range of Tb,app ~ 1016−18 K. For extremely rapid variations, Tb,app can reach up to ~ 1021 K (e.g. Kedziora-Chudczer et al., 1997). Refractive interstellar scintillation may be the most likely extrinsic mechanism (Rickett et al., 1995; Qian, 1994a; Qian, 1994b). Especially for the case of extreme Tb,app (> 1018 K) RISS may be dominant (Dennet-Thorpe and de Bruyn, 2000). However, some IDV events with Tapp ~ 1017−18 K show evidence for an intrinsic origin e.g. the correlated radio-optical intraday variations observed in the BL Lac object 0716+714 (Wagner and Witzel, 1995, Qian et al, 1996). It seems important to distinguish between IDV which is a phenomenon intrinsic to the compact radio sources and IDV which is primarily due to RISS. Multifrequency polarization and VLB I observations would be most helpful (Gabuzda and Kochanev, 1997).

Type
Chapter Three Intra-Day Variability, Gravitational Lensing and Polarization
Information
International Astronomical Union Colloquium , Volume 182: Sources and Scintillations: Refraction and Scattering in Radio Astronomy , 2001 , pp. 119 - 122
Copyright
Copyright © Kluwer 2001

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