2002/07/11 by Lawrence M. Widrow · 931 citations
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Differential rotation #Dynamo #Dynamo theory #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Magnetic field #Physics #Quantum mechanics #Solar and Space Plasma Dynamics #Spiral galaxy #Stars #astro-ph
paper · pdf · doi:10.1103/revmodphys.74.775
published in Reviews of Modern Physics 74(3), 775-823 (American Physical Society) · 67 pages, 17 figures, accepted for publication in Reviews of Modern Physics
arxiv created 2002/07/11 · openalex publication_date 2002/07/30 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/08
A variety of observations suggest that magnetic fields are present in all galaxies and galaxy clusters. These fields are characterized by a modest strength (10^\ensuremath-7--10^\ensuremath-5G) and huge spatial scale (\ensuremath\lesssim1Mpc). It is generally assumed that magnetic fields in spiral galaxies arise from the combined action of differential rotation and helical turbulence, a process known as the \ensuremathα\ensuremathω dynamo. However, fundamental questions concerning the nature of the dynamo as well as the origin of the seed fields necessary to prime it remain unclear. Moreover, the standard \ensuremathα\ensuremathω dynamo does not explain the existence of magnetic fields in elliptical galaxies and clusters. The author summarizes what is known observationally about magnetic fields in galaxies, clusters, superclusters, and beyond. He then reviews the standard dynamo paradigm, the challenges that have been leveled against it, and several alternative scenarios. He concludes with a discussion of astrophysical and early-Universe candidates for seed fields.