Global magnetic structure in spiral galaxies

Global magnetic structure is inferred in spiral galaxies from radio and optical observations. A 3D, quasi-global kinematic dynamo model is developed which demonstrates the possibility of maintaining large-scale magnetic fields by the alpha-omega mechanism. Analytical expressions for large-scale galactic magnetic fields near temporal steady states are derived. Illustrations of the spatial distribution of vector and absolute large-scale magnetic-field strength are presented. When coupled with observations this model can help in understanding the maintenance and morphologies inferred for disk and halo global magnetic fields in spiral galaxies.