Hostname: page-component-78c5997874-xbtfd Total loading time: 0 Render date: 2024-11-10T11:02:54.217Z Has data issue: false hasContentIssue false
  • English
  • Français

Magnetism in galaxies – Observational overview and next generation radio telescopes

Published online by Cambridge University Press:  08 June 2011

Rainer Beck
Rainer Beck*
Affiliation:
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany email: rbeck@mpifr-bonn.mpg.de
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.

The strength and structure of cosmic magnetic fields is best studied by observations of radio continuum emission, its polarization and its Faraday rotation. Fields with a well-ordered spiral structure exist in many types of galaxies. Total field strengths in spiral arms and bars are 20–30 μG and dynamically important. Strong fields in central regions can drive gas inflows towards an active nucleus. The strongest regular fields (10–15 μG) are found in interarm regions, sometimes forming “magnetic spiral arms” between the optical arms. The typical degree of polarization is a few % in spiral arms, but high (up to 50%) in interarm regions. The detailed field structures suggest interaction with gas flows. Faraday rotation measures of the polarization vectors reveals large-scale patterns in several spiral galaxies which are regarded as signatures of large-scale (coherent) fields generated by dynamos. – Polarization observations with the forthcoming large radio telescopes will open a new era in the observation of magnetic fields and should help to understand their origin. Low-frequency radio synchrotron emission traces low-energy cosmic ray electrons which can propagate further away from their origin. LOFAR (30–240 MHz) will allow us to map the structure of weak magnetic fields in the outer regions and halos of galaxies, in galaxy clusters and in the Milky Way. Polarization at higher frequencies (1–10 GHz), to be observed with the EVLA, MeerKAT, APERTIF and the SKA, will trace magnetic fields in the disks and central regions of galaxies in unprecedented detail. All-sky surveys of Faraday rotation measures towards a dense grid of polarized background sources with ASKAP and the SKA are dedicated to measure magnetic fields in distant intervening galaxies and clusters, and will be used to model the overall structure and strength of the magnetic field in the Milky Way.

Keywords

Instrumentation: polarimeterstechniques: polarimetricISM: magnetic fieldsgalaxies: magnetic fieldsgalaxies: spiralradio continuum: galaxiesradio continuum: ISM
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 6 , Symposium S274: Advances in Plasma Astrophysics , September 2010 , pp. 325 - 332
Copyright
Copyright © International Astronomical Union 2011

References

Abreu, P. & The Pierre Auger Collaboration 2010, Astroparticle Physics, 34, 314Google Scholar
Arshakian, T. G., Beck, R., Krause, M., & Sokoloff, D. 2009, A&A, 494, 21Google Scholar
Beck, R. 2007, A&A, 470, 539Google Scholar
Beck, R. 2009, Rev. Mex. AyA, 36, 1Google 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, ARAA, 34, 155Google Scholar
Beck, R., Fletcher, A., Shukurov, A., et al. . 2005, A&A, 444, 739Google Scholar
Bell, E. F. 2003, ApJ, 586, 794Google Scholar
Bernet, M. L., Miniati, F., Lilly, S. J., Kronberg, P. P., & Dessauges-Zavadsky, M. 2008, Nature, 454, 302Google Scholar
Brentjens, M. A. & de Bruyn, A. G. 2005, A&A, 441, 1217Google Scholar
Caprini, C., Durrer, R., & Fenu, E. 2009, J. Cosmology & Astroparticle Physics, 11 (2009) 001CrossRefGoogle Scholar
Chyży, K. T. 2008, A&A, 482, 755Google Scholar
Chyży, K. T. & Beck, R. 2004, A&A, 417, 541Google Scholar
Chyży, K. T. & Buta, R. J. 2008, ApJ, 677, L17CrossRefGoogle Scholar
Dolag, K., Kachelriess, M., Ostapchenko, S., & Tomas, R. 2010, arXiv:1009.1782Google Scholar
Ferguson, A. M. N., Wyse, R. F. G., Gallagher, J. S., & Hunter, D. A. 1998, ApJ, 506, L19Google Scholar
Fletcher, A., Berkhuijsen, E. M., Beck, R., & Shukurov, A. 2004, A&A, 414, 53Google Scholar
Fletcher, A., Beck, R., Shukurov, A., Berkhuijsen, E. M., & Horellou, C. 2010, MNRAS, in pressGoogle Scholar
Gaensler, B. M., Beck, R., & Feretti, L. 2004, New Astr. Revs, 48, 1003CrossRefGoogle Scholar
Gaensler, B. M., Haverkorn, M., Staveley-Smith, L., et al. . 2005, Science, 307, 1610CrossRefGoogle Scholar
Gaensler, B. M., Landecker, T. L., & Taylor, A. R. 2010, BAAS, 42, 470Google Scholar
Gressel, O., Elstner, D., Ziegler, U., & Rüdiger, G. 2008, A&A, 486, L35Google Scholar
Han, J. L., Manchester, R. N., Lyne, A. G., Qiao, G. J. & van Straten, W. 2006, ApJ, 624, 868Google Scholar
Hanasz, M., Wóltański, D., & Kowalik, K. 2009, ApJ, 706, L155Google Scholar
Heesen, V., Krause, M., Beck, R., & Dettmar, R.-J. 2009, A&A, 506, 1123Google Scholar
Heiles, C. & Troland, T. H. 2005, ApJ, 624, 773Google Scholar
Helfer, T. T., Thornley, M. D., Regan, M. W., et al. . 2003, ApJS, 145, 259Google Scholar
Klein, U., Wielebinski, R., & Morsi, H. W. 1988, A&A, 190, 41Google Scholar
Krause, M. 1990, in: Beck, R. et al. . (eds.), Galactic and Intergalactic Magnetic Fields (Dordrecht: Kluwer), p. 187Google Scholar
Krause, M. 1993, in: Krause, F. et al. . (eds.), The Cosmic Dynamo (Dordrecht: Kluwer), p. 303Google Scholar
Krause, M. 2009, Rev. Mex. AyA, 36, 25Google Scholar
Krause, M., Hummel, E., & Beck, R. 1989, A&A, 217, 4Google Scholar
Lacki, B. C., Thompson, T. A., & Quataert, E. 2010, ApJ, 717, 1Google Scholar
Lazar, M., Schlickeiser, R., Wielebinski, R., & Poedts, S. 2009, ApJ, 693, 1133CrossRefGoogle Scholar
Mao, S. A., Gaensler, B. M., Haverkorn, M., et al. . 2010, ApJ, 714, 1170Google Scholar
Murphy, E. 2009, ApJ, 706, 482Google Scholar
Noutsos, A. 2009, in: Strassmeier, K. G. et al. . (eds.), Cosmic Magnetic Fields: From Planets, to Stars and Galaxies (Cambridge: Cambridge Univ. Press), p. 15Google Scholar
Rees, M. J. 2005, in: Wielebinski, R. & Beck, R. (eds.), Cosmic Magnetic Fields (Berlin: Springer), p. 1Google Scholar
Robishaw, T., Quataert, E., & Heiles, C. 2008, ApJ, 680, 981Google Scholar
Schleicher, D. R. G., Banerjee, R., Sur, S., et al. . 2010, A&A, 522, A115Google Scholar
Shukurov, A., Sokoloff, D., Subramanian, K., & Brandenburg, A. 2006, A&A, 448, L33Google Scholar
Soida, M., Beck, R., Urbanik, M., & Braine, J. 2002, A&A, 394, 47Google Scholar
Sokoloff, D. D., Bykov, A. A., Shukurov, A., et al. . 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
Sun, X. H., Reich, W., Waelkens, A. & Enßlin, T.A. 2008, A&A, 477, 573Google Scholar
Tabatabaei, F., Krause, M., Fletcher, A., & Beck, R. 2008, A&A, 490, 1005Google Scholar
Taylor, A. R., Stil, J. M., & Sunstrum, C. 2009, ApJ, 702, 1230Google Scholar
Thompson, T. A., Quataert, E., Waxman, E., Murray, N., & Martin, C. L. 2006, ApJ, 645, 186Google Scholar
Van Eck, C. L., Brown, J. C., Stil, J. M., et al. . 2010, ApJ, in pressGoogle Scholar
Widrow, L. M. 2002, Rev. Mod. Phys., 74, 775Google Scholar
Wolleben, M., Fletcher, A., Landecker, T. L., et al. . 2010, ApJ, 724, L48Google Scholar