Hostname: page-component-586b7cd67f-t7fkt Total loading time: 0 Render date: 2024-11-23T11:44:34.276Z Has data issue: false hasContentIssue false

Radio Intra-Day Variability: Answers and Questions

Published online by Cambridge University Press:  12 April 2016

David L. Jauncey
Affiliation:
Australia Telescope National Facility, CSIRO, Australia. E-mail: [email protected]
Lucyna Kedziora-Chudczer
Affiliation:
Australia Telescope National Facility, and Anglo-Australian Observatory, Epping NSW, Australia. E-mail: [email protected]
James E.J. Lovell
Affiliation:
Australia Telescope National Facility, CSIRO, Australia. E-mail: [email protected]
Jean-Pierre MacQuart
Affiliation:
RCfTA, School of Physics, University of Sydney, NSW, Australia. E-mail: [email protected]
George D. Nicolson
Affiliation:
Harteheesthoek Radio Astronomy Observatory, Krugersdorp, South Africa. E-mail: [email protected]
Rick A. Perley
Affiliation:
National Radio Astronomy Observatory, Socorro, NM, U.S.A.. E-mail: [email protected]
John E. Reynolds
Affiliation:
Australia Telescope National Facility, CSIRO, Australia. E-mail: [email protected]
Anastasios K. Tzioumis
Affiliation:
Australia Telescope National Facility, CSIRO, Australia. E-mail: [email protected]
Mark H. Wieringa
Affiliation:
Australia Telescope National Facility, CSIRO, Australia. E-mail: [email protected]
Hayley E. Bignall
Affiliation:
Department of Physics and Mathematical Physics, University of Adelaide, SA, Australia. E-mail: [email protected]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Intra-day variability (IDV) of active galactic nuclei (AGN) has been detected from gamma-ray energies to radio wavelengths. At high energies, such variability appears to be intrinsic to the sources themselves. However, at radio wavelengths, brightness temperatures as high as 1018 to 1021 K are encountered if the IDV is intrinsic to the source. We discuss here the accumulating evidence showing that, at radio wavelengths where the highest brightness temperatures are encountered, interstellar scintillation (ISS) is the principal mechanism causing IDV. While ISS reduces the implied brightness temperatures, they still remain uncomfortably high.

Type
Chapter Three Intra-Day Variability, Gravitational Lensing and Polarization
Copyright
Copyright © Kluwer 2001

References

Dennett-Thorpe, J. and De Bruyn, A.G.: 2000, Astrophys. J. 529, L65.CrossRefGoogle Scholar
Dent, W.A.: 1965, Science 148, 1458.CrossRefGoogle Scholar
Heeschen, D.S.: 1984, Astron. J. 89, 1111.CrossRefGoogle Scholar
Heeschen, D.S. and Rickett, B.J.: 1987, Astron. J. 93, 589.CrossRefGoogle Scholar
Jauncey, D.L., et al: 2000, in: Hirabayashi, H., Edwards, P.G. and Murphy, D.W. (eds.), Astrophysical Phenomena Revealed by Space VLBI, 147.Google Scholar
Kedziora-Chudezcr, L., et al: 1997, Astrophys. J. 490, L9.CrossRefGoogle Scholar
Kedziora-Chudczer, L., et al: 1998, IAU Circular, 7066.Google Scholar
Kedziora-Chudezcr, L., et al.: Mon. Not. R. Astron. Soc, submitted.Google Scholar
Kellcrmann, K.I. and Pauliny-Toth, I.I.K.: 1969, Astrophys. J. 155, L71.CrossRefGoogle Scholar
Kellermann, K.I., et al: 2000, in: Hirabayashi, H., Edwards, P.G. and Murphy, D.W. (eds.), Astrophysical Phenomena Revealed by Space VLBI, 158.Google Scholar
Lovell, J.E.J., et al: 2000, in: Hirabayashi, H., Edwards, P.G. and Murphy, D.W. (eds.), Astrophysical Phenomena Revealed by Space VLBI, 183.Google Scholar
Macquart, J.-P, et al.: 2000, Astrophys. J. 538, 623.CrossRefGoogle Scholar
Marscher, A.P., et al.: 2000, in: Hirabayashi, H., Edwards, P.G. and Murphy, D.W. (eds.), Astrophysical Phenomena Revealed by Space VLBI, 39.Google Scholar
Preston, R.A., et al.: 2000, in: Hirabayashi, H., Edwards, P.G. and Murphy, D.W. (eds.), Astrophysical Phenomena Revealed by Space VLBI, 199.Google Scholar
Qian, S.J., et al.: 1991, Astron. Astrophys. 241, 15.Google Scholar
Quirrenbach, A., Witzel, A., Wagner, S., et al.: 1991, Astrophys. J. 372, L71.CrossRefGoogle Scholar
Quirrenbach, A., et al.: 1992, Astron. Astrophys. 258, 279.Google Scholar
Quirrenbach, A., et al: 2000, Astron. Astrophys. Suppl. Ser. 141, 221.CrossRefGoogle Scholar
Readhead, A.C.S.: 1994, Astrophys. J. 426, 51.CrossRefGoogle Scholar
Rees, M.J.: 1966, Nature 211, 468.CrossRefGoogle Scholar
Rickett, B.J., et al: 1995, Astron. Astrophys. 293, 479.Google Scholar
Wagner, S.J. and Witzel, A.: 1995, Annu. Rev. Astron. Astrophys. 33, 163.CrossRefGoogle Scholar
Wagner, S.J., Witzel, A., Heidt, J., Krichbaum, et al: 1996, Astron. J. 1ll, 2187.CrossRefGoogle Scholar
Walker, M.A.: 1998, Mon. Not. R. Astron. Soc. 294, 307.CrossRefGoogle Scholar
Witzel, A., et al.: 1986, Mitt. Astron. Ges. 65, 239.Google Scholar