Hostname: page-component-78c5997874-g7gxr Total loading time: 0 Render date: 2024-11-19T03:22:55.417Z Has data issue: false hasContentIssue false
  • English
  • Français

Measuring interstellar magnetic fields by radio synchrotron emission

Published online by Cambridge University Press:  01 November 2008

Rainer Beck
Rainer Beck*
Affiliation:
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany email: [email protected]
Rights & Permissions [Opens in a new window]

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.

Radio synchrotron emission, its polarization and its Faraday rotation are powerful tools to study the strength and structure of interstellar magnetic fields. The total intensity traces the strength and distribution of total magnetic fields. Total fields in gas-rich spiral arms and bars of nearby galaxies have strengths of 20–30 μGauss, due to the amplification of turbulent fields, and are dynamically important. In the Milky Way, the total field strength is about 6 μG near the Sun and several 100 μG in filaments near the Galactic Center. – The polarized intensity measures ordered fields with a preferred orientation, which can be regular or anisotropic fields. Ordered fields with spiral structure exist in grand-design, barred, flocculent and even in irregular galaxies. The strongest ordered fields are found in interarm regions, sometimes forming “magnetic spiral arms” between the optical arms. Halo fields are X-shaped, probably due to outflows. – The Faraday rotation of the polarization vectors traces coherent regular fields which have a preferred direction. In some galaxies Faraday rotation reveals large-scale patterns which are signatures of dynamo fields. However, in most galaxies the field has a complicated structure and interacts with local gas flows. In the Milky Way, diffuse polarized radio emission and Faraday rotation of the polarized emission from pulsars and background sources show many small-scale and large-scale magnetic features, but the overall field structure in our Galaxy is still under debate.

Keywords

Techniques: polarimetric – ISM: magnetic fields – galaxies: magnetic fields – galaxies: spiral – radio continuum: galaxies
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 4 , Symposium S259: Cosmic Magnetic Fields: From Planets, to Stars and Galaxies , November 2008 , pp. 3 - 14
Copyright
Copyright © International Astronomical Union 2009

References

Arshakian, T. G., Beck, R., Krause, M., & Sokoloff, D. 2008, A&A, in press, arXiv:0810.3114Google Scholar
Battaner, E. & Florido, E. 2000, Fund. Cosmic Phys. 21, 1Google Scholar
Beck, R. 2005, in: Wielebinski, R., & Beck, R. (eds.), Cosmic Magnetic Fields, Lecture Notes in Physics (Berlin: Springer) vol. 664, p. 41CrossRefGoogle Scholar
Beck, R. 2007, A&A 470, 539Google Scholar
Beck, R. 2008, Rev. Mexicana AyA, in press, arXiv:0804.4594Google Scholar
Beck, R. & Gaensler, B. M. 2004, New Astron. Revs 48, 1289CrossRefGoogle Scholar
Beck, R. & Golla, G. 1988, A&A 191, L9Google Scholar
Beck, R. & Hoernes, P. 1996, Nature 379, 47CrossRefGoogle Scholar
Beck, R. & Krause, M. 2005, AN 326, 414Google Scholar
Beck, R., Brandenburg, A., Moss, D., Shukurov, A., & Sokoloff, D. 1996, ARA&A 34, 155Google Scholar
Beck, R., Shukurov, A., Sokoloff, D., & Wielebinski, R. 2003, A&A 411, 99Google Scholar
Beck, R., Fletcher, A., Shukurov, A., et al. 2005, A&A 444, 739Google Scholar
Bell, E. F. 2003, ApJ 586, 794CrossRefGoogle Scholar
Berkhuijsen, E. M., Beck, R., & Hoernes, P. 2003, A&A 398, 937Google Scholar
Bernet, M. L., Miniati, F., Lilly, S. J., Kronberg, P. P., & Dessauges-Zavadsky, M. 2008, Nature 454, 302CrossRefGoogle Scholar
Brentjens, M. A. & de Bruyn, A. G. 2005, A&A 441, 1217Google Scholar
Brown, J. C., Haverkorn, M., Gaensler, B. M., et al. 2007, ApJ 663, 258CrossRefGoogle Scholar
Chyży, K. T. & Beck, R. 2004, A&A 417, 541Google Scholar
Chyży, K. T. & Buta, R. J. 2008, ApJ 677, L17CrossRefGoogle Scholar
Chyży, K. T., Bomans, D. J., Krause, M., et al. 2007, A&A 462, 933Google Scholar
Dalla Vecchia, C. & Schaye, J. 2008, MNRAS 387, 1431CrossRefGoogle Scholar
de Avillez, M. A. & Breitschwerdt, D. 2005, A&A 436, 585Google Scholar
de Jong, T., Klein, U., Wielebinski, R., & Wunderlich, E. 1985, A&A 147, L6Google Scholar
Dobbs, C. L. & Price, D. J. 2008, MNRAS 383, 497CrossRefGoogle Scholar
Dumke, M., Krause, M., Wielebinski, R. & Klein, U. 1995, A&A 302, 691Google Scholar
Elstner, D., Meinel, R., & Beck, R. 1992, A&AS 94, 587Google Scholar
Ferguson, A. M. N., Wyse, R. F. G., Gallagher, J. S., & Hunter, D. A. 1998, ApJ 506, L19CrossRefGoogle Scholar
Fletcher, A. & Shukurov, A. 2006, MNRAS 371, L21CrossRefGoogle Scholar
Fletcher, A., Berkhuijsen, E. M., Beck, R., & Shukurov, A. 2004, A&A 414, 53Google Scholar
Frick, P., Beck, R., Berkhuijsen, E. M., & Patrikeev, I. 2001, MNRAS 327, 1145CrossRefGoogle Scholar
Gaensler, B. M., Haverkorn, M., Staveley-Smith, L., et al. 2005, Science 307, 1610CrossRefGoogle Scholar
Han, J. L., Manchester, R. N., Berkhuijsen, E. M., & Beck, R. 1997, A&A 322, 98Google Scholar
Han, J.L., Manchester, R. N., Lyne, A. G., & Qiao, G. J. 2002, ApJ 570, L17CrossRefGoogle Scholar
Haverkorn, M., Gaensler, B. M., Brown, J. C., et al. 2006, ApJ 637, L33CrossRefGoogle Scholar
Heesen, V., Beck, R., Krause, M., & Dettmar, R.-J. 2008, A&A, in press, arXiv:0812.0346Google Scholar
Heiles, C. 1996, in: Roberge, W. G., & Whittet, D. C. B. (eds.), Polarimetry of the Interstellar Medium, ASP Conf. Ser. (San Francisco: Astron. Soc. Pac.), vol. 97, p. 457Google Scholar
Helou, G. & Bicay, M. D. 1993, ApJ 415, 93CrossRefGoogle Scholar
Hoernes, P., Berkhuijsen, E. M., & Xu, C. 1998, A&A 334, 57Google Scholar
Hughes, A., Wong, T., Ekers, R., et al. 2006, MNRAS 370, 363CrossRefGoogle Scholar
Johnston-Hollitt, M., Hollitt, C. P., & Ekers, R.D. 2004, in: Uyaniker, B., Reich, W. & Wielebinski, R. (eds.), The Magnetized Interstellar Medium (Katlenburg: Copernicus), p. 13Google Scholar
Kiepenheuer, K. O. 1950, Phys. Rev. 79, 738CrossRefGoogle Scholar
Klein, U., Wielebinski, R. & Morsi, H. W. 1988, A&A 190, 41Google Scholar
Kothes, R., Landecker, T. L., Reich, W., Safi-Harb, S., & Arzoumanian, Z. 2008, ApJ 687, 516CrossRefGoogle Scholar
Krause, F. & Beck, R. 1998, A&A 335, 789Google Scholar
Krause, M. 1990, in: Beck, R., Wielebinski, R., & Kronberg, P. P. (eds.), Galactic and Intergalactic Magnetic Fields (Dordrecht: Kluwer), p. 187CrossRefGoogle Scholar
Krause, M. 2008, Rev. Mexicana AyA, in press, arXiv:0806.2060Google Scholar
Krause, M., Hummel, E., & Beck, R. 1989, A&A 217, 4Google Scholar
Kronberg, P. P., Bernet, M. L., Miniati, F., et al. 2008, ApJ 676, 70CrossRefGoogle Scholar
Lisenfeld, U., Völk, H. J., & Xu, C. 1996a, A&A 306, 677Google Scholar
Lisenfeld, U., Völk, H. J., & Xu, C. 1996b, A&A 314, 745Google Scholar
Men, H., Ferrière, K., & Han, J. L. 2008, A&A 486, 819Google Scholar
Moss, D. & Sokoloff, D. 2008, A&A 487, 197Google Scholar
Nieten, C., Neininger, N., Guélin, M., et al. 2006, A&A 453, 459Google Scholar
Niklas, S. & Beck, R. 1997, A&A 320, 54Google Scholar
Patrikeev, I., Fletcher, A., Stepanov, R., et al. 2006, A&A 458, 441Google Scholar
Rand, R. J. & Lyne, A. G. 1994, MNRAS 268, 497CrossRefGoogle Scholar
Ransom, R. R., Uyaniker, B., Kothes, R., & Landecker, T. L. 2008, ApJ 684, 1009CrossRefGoogle Scholar
Reich, W. 1994, in: Genzel, R., & Harris, A. I. (eds.), The Nuclei of Normal Galaxies (Dordrecht: Kluwer), p. 55CrossRefGoogle Scholar
Robishaw, T., Quataert, E. & Heiles, C. 2008, ApJ 680, 981CrossRefGoogle Scholar
Roussel, H., Helou, G., Beck, R., et al. 2003, ApJ 593, 733CrossRefGoogle Scholar
Seymour, N., Dwelly, T., Moss, D., et al. 2008, MNRAS 386, 1695CrossRefGoogle Scholar
Soida, M., Beck, R., Urbanik, M. & Braine, J. 2002, A&A 394, 47Google Scholar
Sokoloff, D. D., Bykov, A. A., Shukurov, A., Berkhuijsen, E. M., Beck, R., & Poezd, A. D. 1998, MNRAS 299, 189, and Erratum in MNRAS 303, 207CrossRefGoogle Scholar
Stepanov, R., Arshakian, T. G., Beck, R., Frick, P., & Krause, M. 2008, A&A 480, 45Google Scholar
Stil, J. M., Krause, M., Beck, R., & Taylor, A. R. 2008, ApJ, in press, arXiv:0810.2303Google Scholar
Sun, X. H., Reich, W., Waelkens, A., & Enßlin, T. A. 2008, A&A 477, 573Google Scholar
Tabatabaei, F., Beck, R., Krause, M., et al. 2007a, A&A 466, 509Google Scholar
Tabatabaei, F., Beck, R., Krügel, E., et al. 2007b, A&A 475, 133Google Scholar
Tabatabaei, F., Krause, M., Fletcher, A., & Beck, R. 2008, A&A 490, 1005Google Scholar
Thompson, T. A., Quataert, E., Waxman, E., Murray, N., & Martin, C.L. 2006, ApJ 645, 186CrossRefGoogle Scholar
Walsh, W., Beck, R., Thuma, G., et al. 2002, A&A 388, 7Google Scholar
Wielebinski, R. 2005, in: Wielebinski, R., & Beck, R. (eds.), Cosmic Magnetic Fields, Lecture Notes in Physics (Berlin: Springer) vol. 664, p. 89CrossRefGoogle Scholar
Wolleben, M. & Reich, W. 2004, A&A 427, 537Google Scholar