1999A&A...345..461S

We present 10.55GHz observations of the strong-density-wave spiral NGC 3627. Total power and polarization maps with a resolution of 1.13', sensitive to a weak extended emission were obtained. In the analysis we used also available data in the CO and Hα lines. The total power brightness distribution shows two equally bright sources close to the bar ends, coincident with similar peaks in CO and Hα. The strong central peak of the CO emission does not correspond to a detectable central source in radio continuum. A weak Hα flux from this region is thus due not only to a strong absorption but may also indicate a low star formation level in the central molecular complex. The equally strong total power peaks at the bar ends do not reflect the asymmetry of the Hα emission, the latter being stronger at the northern bar end. The Hα asymmetry is likely to be due to differences in absorption. The polarized emission has the form of two asymmetric lobes with B-vectors running parallel to the optical arms. The stronger lobe is located at the position of the dust lane in the western arm while the weaker one falls on the middle of the interarm space in the NE disk. Smooth polarized emission away from any spiral structures was also detected. Despite the strong density waves, many polarization properties of this galaxy like the large-scale distribution of polarized intensity or azimuthal variations of magnetic pitch angles can be reasonably explained by the presence of an axisymmetric, dynamo-type magnetic field component. However, extra effects like the depolarization of the southern segment of the eastern arm by vertical fields above star-forming regions, as well as some compressional enhancement of regular fields in the western arm seem necessary to explain our polarization data.