Hostname: page-component-78c5997874-94fs2 Total loading time: 0 Render date: 2024-11-18T07:35:21.860Z Has data issue: false hasContentIssue false
  • English
  • Français

QSQs and Radio Galaxies - their Spectra and Time Variations at Radio Frequencies

Published online by Cambridge University Press:  14 August 2015

Beverley J. Harris
Beverley J. Harris*
Affiliation:
Mt. Stromlo and Siding Spring Observatories, The Australian National University, Canberra, Australia and The Ohio State University Radio Observatory, Columbus, O., U.S.A.

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.

Accurate relative spectra for 300 radio sources from the Parkes catalogue have been measured and a statistical study made of their relation to class of optical identification and to other radio properties. Individual spectra and their time variations have also been investigated.

The results support the contention that radio sources for which no identification appears on the Palomar Sky Survey prints may be galaxies more luminous at radio frequencies than those which are identified. From a study of QSOs, radio galaxies and these blank field objects, it appears (a) that with increasing radio luminosity compact components are more often found, their presence being indicated by synchrotron self-absorption at low and high frequencies, by flat, variable spectra at high frequencies, and by interplanetary scintillations; and (b) that where no compact component contributes to the spectrum at high frequencies, many spectra steepen with increasing frequency, an effect which may be more marked for the more radio luminous objects.

Detailed analyses of the time variations in the compact components of 22 variable sources are generally consistent with the adiabatically expanding, uniform sphere model of Shklovsky, Kellermann, van der Laan and others. The model was modified to include relativistic expansion according to the formulae given by Rees and Simon. The results suggest that these components have evolved within months or years, have linear dimension of 0.1 to 100 pc and magnetic fields of 1 to 10−4 G. Some spectra at frequencies above 5000 MHz suggest non-adiabatic expansion which may be the result of continued injection of energy into an expanding region.

Type
Research Article
Information
Symposium - International Astronomical Union , Volume 44: External Galaxies and Quasi-Stellar Objects , 1972 , pp. 232 - 248
Copyright
Copyright © Reidel 1972 

References

Clark, B. G., Kellermann, K. I., Bare, C. C., Cohen, M. H., and Jauncey, D. L.: 1968, Astrophys. J. 153, 705.Google Scholar
Colgate, S. A.: 1968, Astrophys. J. 73, 905.Google Scholar
Dent, W. A. and Haddock, F. T.: 1966, Astrophys. J. 144, 568.CrossRefGoogle Scholar
Ekers, R. D.: 1969, Australian J. Phys. Suppl. 6.Google Scholar
Gardner, F. F. and Whiteoak, J. B.: 1969, Australian J. Phys. 22, 107.CrossRefGoogle Scholar
Harris, B. J.: 1970a, b, c, in preparation.Google Scholar
Heeschen, D. S.: 1966, Astrophys. J. 146, 517.Google Scholar
Hobbs, R. W., Corbett, W. W., and Santini, N. J.: 1968, Astrophys. J. 152, 43.Google Scholar
Kellermann, K. I.: 1964, Publ. Owens Valley Radio Obs. 1, No. 2.Google Scholar
Kellermann, K. I.: 1966, Astrophys. J. 146, 621.CrossRefGoogle Scholar
Kellermann, K. I., Clark, B. G., Bare, C. C., Rydbeck, O., Ellder, J., Hansson, B., Kollberg, E., Hoglund, B., Cohen, M. H., and Jauncey, D. L.: 1968, Astrophys. J. 153, L209.Google Scholar
Kellermann, K. I. and Pauliny-Toth, I. I. K.: 1968, Ann. Rev. Astron. Astrophys. 6, 417.Google Scholar
Kellermann, K. I., Pauliny-Toth, I. I. K., and Williams, P. J. S.: 1969, Astrophys. J. 157, 1.Google Scholar
Locke, J. L., Andrew, B. H., and Medd, W. J.: 1969, Astrophys. J. 157, L81.Google Scholar
Longair, M. S. and Macdonald, G. H.: 1969, Monthly Notices Roy. Astron. Soc. 145, 309.Google Scholar
Macdonald, G. H., Kenderdine, S., and Neville, A. C.: 1968, Monthly Notices Roy. Astron. Soc. 138, 259.Google Scholar
Medd, W. J., Locke, J. L., Andrew, B. H., and van den Bergh, S.: 1968, Astron. J. 73, 293.Google Scholar
Morris, D. and Whiteoak, J. B.: 1968, Australian J. Phys. 21, 475.Google Scholar
Rees, M. J. and Simon, M.: 1968, Astrophys. J. 152, L145.CrossRefGoogle Scholar
Seielstad, G. A. and Weiler, K. W.: 1969, Astrophys. J. Suppl. Ser. 18, 85.Google Scholar
Shimmins, A. J.: 1968, Astrophys. Letters 2, 157.Google Scholar
Woltjer, L.: 1966, Astrophys. J. 146, 597.Google Scholar