a2 School of Mathematics and Statistics, Newcastle University, Newcastle upon Tyne, NE1 7RU, U.K., email: email@example.com
Using high-resolution data of the linearly polarized intensity and polarization angle at 3.6, 6.2, and 20 cm together with a 3-D model of the regular magnetic field, we study variations of the structure, strength, and energy density of the magnetic field in the Scd galaxy M 33. The regular magnetic field consists of a horizontal component (represented by an axisymmetric mode from 1 to 3 kpc radius and a superposition of axisymmetric and bisymmetric modes from 3 to 5 kpc radius) and a vertical component. However, the inferred ‘vertical field’ may be partly due to a galactic warp. We estimate the average total and regular magnetic field strengths as 6.4 and 2.5 μG, respectively. Generation of interstellar magnetic fields by turbulent gas motion in M 33 is indicated as the turbulent and magnetic energy densities are about equal.