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Radio Continuum Surveys of the Galaxy and Galaxies

Published online by Cambridge University Press:  26 May 2016

Richard Wielebinski
Richard Wielebinski*
Affiliation:
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany

Abstract

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Radio sky surveys give us basic information about the origin of the radio emission from the Galaxy. By mapping the sky at several radio frequencies a separation of the thermal and non-thermal emission components is possible. The major part of the low-frequency radio emission comes from the synchrotron process, the braking of relativistic electrons in magnetic fields. By mapping the linear polarization at several frequencies (required for the correction of the Faraday rotation) the orientation of the magnetic fields in the emitting regions can be deduced. Older all-sky surveys at 30, 150 and 408 MHz have now been supplemented by new observations of the Galaxy at 45 and 1420 MHz. These surveys, in addition to being important as tracers of the morphology of the magnetic fields in the Galaxy, are also required to correct for the ‘foreground’ features in cosmological studies of the COBE data and the PLANCK surveys in the future. Studies of the Galaxy in polarization have been made some years ago indicating high percentage of linear polarization in various directions. More recent work with good angular resolution has shown spectacular polarized intensity structures in selected regions. Low-frequency data with good angular resolution are urgently required for the interpretation of these features.

Observations of nearby galaxies in radio continuum (both total power and polarized intensity) have given us the possibility to study magnetic fields in objects at known distances. Polarization observations of nearby galaxies have confirmed the existence of regular magnetic fields in practically every object so far studied. Originally data were obtained from large single-dish telescopes, notably from Effelsberg and Parkes. These data were greatly enhanced by the addition of higher resolution components from the VLA and ATCA respectively. These results indicate surprisingly homogeneous magnetic fields in most galaxies. High angular resolution observations with the GMRT at lower radio frequencies will add a new dimension to the data on galaxies.

Type
Part 5: Galactic Surveys and Extended Emission
Information
Symposium - International Astronomical Union , Volume 199: The Universe at Low Radio Frequencies , 2002 , pp. 262 - 267
Copyright
Copyright © Astronomical Society of the Pacific 2002 

References

Beck, R., Berkhuijsen, E.M., & Wielebinski, R. 1978 A&A, 68, L27 Google Scholar
Beck, R., Berkhuijsen, E.M., & Wielebinski, R. 1980, Nature, 283, 272 Google Scholar
Beck, R., & Hoernes, P. 1996, Nature, 379, 47 CrossRefGoogle Scholar
Beck, R., Brandenburg, A., Moss, D. et al. 1996, ARA&A, 34, 153 Google Scholar
Beck, R., Berkhuijsen, E.M., & Hoernes, P. 1998, A&AS, 129, 329 Google Scholar
Brouw, W.N., & Spoelstra, T.A. Th. 1976, A&AS, 26, 129 Google Scholar
Cane, H.V. 1978, Aust. J. Phys., 31, 561 CrossRefGoogle Scholar
Condon, J.J. 1987, ApJS, 65, 485 Google Scholar
Dröge, F., & Priester, W. 1956, Zeitschrift f. Phys., 40, 236 Google Scholar
Duncan, A.R., Reich, P., Reich, W., & Fürst, E. 1999, A&A, 350, 447 Google Scholar
Dumke, M., Krause, M., Wielebinski, R., & Klein, U. 1995, A&A, 302, 691 Google Scholar
Haslam, C.G.T., Salter, C.J., Stoffel, H., & Wilson, W.E. 1982, A&AS, 47, 1 Google Scholar
Landecker, T.L., & Wielebinski, R. 1970, Aust. J. Phys. Suppl. No. 16 Google Scholar
Maeda, K., Alvarez, H., Aparici, J. et al. 1999, A&AS, 140, 145 Google Scholar
Mathewson, D.S., & Milne, D.K. 1965, Aust. J. Phys., 18, 635 CrossRefGoogle Scholar
Niklas, S., Klein, U., Braine, J., & Wielebinski, R. 1995, A&AS, 114, 21 Google Scholar
Seiradakis, J.H., Reich, W., Wielebinski, R. et al. 1989, A&AS, 81, 291 Google Scholar
Sokoloff, D.D., Bykov, A.A., Shukurov, A. et al. 1998, MNRAS, 299, 189 Google Scholar
Testori, J.C., Reich, P. et al. 2000 (in preparation) Google Scholar
Uyaniker, B., Fürst, E., Reich, W. et al. 1998, A&AS, 132, 401 Google Scholar
Uyaniker, B., Fürst, E., Reich, W. et al. 1999, A&AS, 138, 31 Google Scholar
Westerhout, G., Seeger, Ch.L., Brouw, W.N. et al. 1962, Bull. Astr. Inst. Ned., 16, 187 Google Scholar
Wielebinski, R., & Krause, F. 1993 A&AR, 4, 449 Google Scholar
Wielebinski, R., & Shakeshaft, J.R. 1964, MNRAS, 268, 19 Google Scholar
Wielebinski, R., Shakeshaft, J.R., & Pauliny-Toth, I.I.K. 1962, Observatory, 82, 158 Google Scholar
Wieringa, M.H., de Bruyn, A.G., Jansen, D. et al. 1993, A&A, 268, 215 Google Scholar